Methods and systems for NVH-based vehicle powertrain control

ABSTRACT

Methods and systems are provided for adjusting noise, vibration, and harshness (NVH) limits for a vehicle based on an occupancy level of the vehicle. The occupancy level is inferred based on a number of occupants and their position within a vehicle, and further based on a degree of interaction of a primary occupant with vehicle controls. As the occupancy level decreases, NVH constraints for operating the vehicle are reduced and one or more vehicle operating parameters nay be based on the reduced NVH constraints.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 62/695,612, entitled “Methods and Systems for NVH-Based VehiclePowertrain Control”, and filed on Jul. 9, 2018. The entire contents ofthe above-listed application are hereby incorporated by reference forall purposes.

FIELD

The present description relates generally to methods and systems forcontrolling a vehicle engine and an associated powertrain during anautonomous mode of operation.

BACKGROUND/SUMMARY

Noise, Vibration, and Harshness (NVH) behavior of a vehicle issignificantly influenced by the vehicle's powertrain. For example, NVHmay result from vibration due to combustion quality issues, torqueconverter operation, variable displacement cylinder switching,transmission gear shifting, etc. For example, cylinder deactivationcauses lower frequency and higher amplitude torque vibrations at thecrankshaft. These vibrations can be transmitted through components suchas seats, steering wheel etc., to the vehicle occupants, therebygenerating undesirable noise within the vehicle cabin. As anotherexample, transmissions experience noises such as gear meshing noise andpump noise. Furthermore, gasoline engines experience noise from sourcessuch as direct-injection fuel systems. To improve driver perception ofvehicle drivability and performance, vehicle powertrains may be designedand calibrated to operate in a state where NVH is reduced, such as wheredriver and passenger experienced NVH is balanced with engine output andemissions efficiency. As an example, variable displacement operation maybe limited to certain engine operating regions, such as mid-range enginespeeds at low or moderate loads. Additionally, the induction ratiosavailable during a variable displacement mode may be limited in view ofthe NVH constraints.

However, the inventors have recognized that the methods that limit NVHalso have a negative impact on fuel economy. In other words, theinstantaneous balance of NVH and other engine attributes can constrainthe realized engine efficiency from a theoretical optimal efficiency.That is, when NVH constraints are imposed, fuel economy improvement isreduced. As a result, there is a trade-off between NVH and fuel economy,and the NVH limit becomes the limit for fuel economy improvement that agiven technology can provide. With reference to the earlier example, anoperating range of fuel saving technologies, such as VDE, is limited dueto imposed NVH constraints, reducing the associated fuel economyimprovement that can be achieved.

Further, it is assumed that an occupant, such as a primary vehicledriver, will be in the vehicle the entire time that the vehicle ismoving, and thus, the NVH limit for a given operation is set and doesnot change during the lifetime of the vehicle. However, the inventorshave recognized that in vehicles with autonomous driving capabilities,the assumption that an occupant will be in the vehicle does not hold.For example, the vehicle may be operated in an autonomous mode withoutany occupant between passenger pick-up locations or while transferringgoods. In addition, the NVH perception for a vehicle driver may besignificantly different from that of a vehicle passenger, such as anoccupant sitting in a passenger row (behind the driver's seat).Furthermore, the NVH perception of the driver may vary based on howactively they are involved in driving the vehicle. Specifically, NVH istransmitted to an occupant through various vehicle surfaces, such as aseat, a steering wheel, accelerator and brake pedals, cabin walls, etc.If an occupant is not actively interacting with these vehicle surfaces,such as when an occupant is a passenger in a rear seat, or when a driveris controlling the steering wheels while a vehicle controller controlspedal application (e.g., while in the autonomous mode of vehicleoperation), the expected NVH is not experienced. During such conditions,the active controls to limit NVH can severely impact fuel economywithout making a significant increase in driver comfort.

In one example, the issues described above may be addressed by a methodfor operating a vehicle, comprising: during an autonomous mode ofvehicle operation, estimating an occupancy level of the vehicle based ona number of occupants, a position of each occupant within the vehicle,and a drive activity level of a primary occupant; and altering noise,vibration, and harshness (NVH) limits for a powertrain of the vehicleresponsive to the occupancy level. In this way, drivability may becompromised when low vehicle occupancy is detected in order to improvefuel economy.

As one example, when a vehicle is operating in autonomous mode, NVHconstraints limiting fuel economy for a given technology may be relaxedby an order based on the occupancy level of the vehicle in order toimprove fuel economy. A vehicle controller may identify an occupancylevel of the vehicle based on a number of occupants in the vehicle,their position within the cabin (e.g., whether they are in a driver seator a passenger seat), and further based on their interactions withvehicle surfaces through which NVH is transmitted (such as based onwhether a driver is actuating the steering and/or pedals). The occupancylevel may be further adjusted based on the presence of cargo. Theoccupancy level may be determined based on input from various vehiclesensors, such as occupancy sensors, infra-red sensors, microphones, andcapacitive touch sensors, as well as based on steering input, brakeinput, accelerator input, etc. Powertrain calibration settings may thenbe adjusted based on the occupancy level so as to bias vehicle operatingattributes towards smooth and silent operation for increased passengercomfort (or to protect fragile cargo) when the occupancy level ishigher. The settings may alternatively be biased towards energyefficiency, while reducing NVH constraints, when the occupancy level islower. As one example, when the occupancy level is higher (such as whena driver is actively involved in steering and pedal control),transmission shifts may be completed relative more slowly with the useof more torque-compensating spark retard to enable a smoothertransition. In comparison, when the occupancy level is lower (such aswhen the only occupant of an autonomously operating vehicle is apassenger), transmission shifts may be completed substantiallyinstantaneously with the use of less torque-compensating spark retard(e.g., with no spark retard). As other examples, with variably reducedNVH constraints, the operating range of one or more of variabledisplacement operation, deceleration fuel shut off, exhaust gasrecirculation, etc., may be expanded to provide greater fuel economyimprovement while compromising NVH. Further, torque converter slip maybe adjusted towards less slip to improve fuel economy by reducing torqueloss. Furthermore, a system battery may be charged more aggressively,such as by enabling regenerative braking to be extended to lower gearsand lower vehicle speeds. As a result, the vehicle may improve fueleconomy while balancing NVH to levels that are acceptable based on theoccupancy level.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example vehicle propulsion system;

FIG. 1B shows a schematic diagram of an engine;

FIG. 2 shows an example vehicle driveline configuration;

FIG. 3 shows a flowchart illustrating an example method for adjustingpowertrain calibration based on a detected occupancy level of a vehicle;

FIG. 4 shows a flowchart illustrating an example method for determiningan occupancy level of a vehicle;

FIG. 5 shows a flowchart illustrating an example method for controllingexhaust gas recirculation settings of the vehicle with reduced NVHconstraints at lower vehicle occupancy levels;

FIG. 6A shows a flowchart illustrating an example method for controllingvariable displacement engine (VDE) operation of the vehicle with reducedNVH constraints at lower vehicle occupancy levels;

FIG. 6B shows a graph illustrating an example operating range of VDEwith reduced NVH constraints at lower vehicle occupancy levels;

FIG. 7A shows a flowchart illustrating an example method for controllingtorque converter operation of the vehicle with reduced NVH constraintsat lower vehicle occupancy levels;

FIG. 7B shows a graph illustrating an example adjustment of a torqueconverter slip schedule with reduced NVH constraints at lower vehicleoccupancy levels;

FIG. 8A shows a flowchart illustrating an example method for controllingnoise vibration and harshness (NVH) of the vehicle during luggingconditions with reduced NVH constraints at lower vehicle occupancylevels;

FIG. 8B shows a graph illustrating an example adjustment of lugging NVHthresholds based on vehicle occupancy levels;

FIG. 9 shows a flowchart illustrating an example method for controllinga transmission shift schedule with reduced NVH constraints at lowervehicle occupancy levels;

FIG. 10 shows a flowchart illustrating an example method for controllingdeceleration fuel shut off (DFSO) operation of the vehicle with reducedNVH constraints at lower vehicle occupancy levels;

FIG. 11 shows a flowchart illustrating an example method for controllingthe schedule of on-board diagnostic routines of the vehicle with reducedNVH constraints at lower vehicle occupancy levels;

FIG. 12 shows a flowchart illustrating an example method for controllinghybrid vehicle operation with reduced NVH constraints at lower vehicleoccupancy levels; and

FIG. 13 shows a prophetic example of adjusting vehicle powertrainsettings based on occupancy level.

DETAILED DESCRIPTION

The following description relates to systems and methods for adjustingvehicle operation to alter a balance between fuel economy and noise,vibration, and harshness (NVH) of a vehicle, such as the vehicle shownin FIG. 1A, based on an occupancy level of the vehicle. The vehicle mayinclude an occupant sensing system for detecting a number of occupantspresent in the vehicle, determining whether the occupant is a driver ora passenger, and determining whether the driver is actively controllingthe steering and the pedals. Responsive to a lower occupancy level,vehicle operation may be adjusted to increase fuel economy improvementwhile compromising NVH. Adjusting vehicle operation may includeadjusting the calibration of one or more electronically controlleddevices in a driveline of the vehicle, such as the driveline shown inFIG. 2, and settings for an engine, such as the engine shown in FIG. 1B.A vehicle controller may be configured to perform a routine, such asexample routine of FIGS. 3 and 4, to determine an occupancy level of thevehicle based on sensor input, and adjust one or more vehicle operatingparameters based on the determined occupancy level. Example adjustmentsto powertrain calibration and settings is shown with reference to FIGS.5-12. A prophetic example of engine adjustments during vehicle operationis shown at FIG. 13.

FIG. 1A illustrates an example vehicle propulsion system 100. Vehiclepropulsion system 100 includes a fuel burning engine 110 and a motor120. While the vehicle propulsion system 100 illustrated in FIG. 1A is ahybrid-propulsion system, it will be appreciated that the embodimentsdescribed herein, including the methods described with respect to FIGS.3-12 are applicable to vehicle propulsion systems that are solely drivenby an engine and are configured with autonomous driving capability.

As a non-limiting example, engine 110 comprises an internal combustionengine and motor 120 comprises an electric motor. Motor 120 may beconfigured to utilize or consume a different energy source than engine110. For example, engine 110 may consume a liquid fuel (e.g., gasoline)to produce an engine output while motor 120 may consume electricalenergy to produce a motor output. As such, a vehicle with propulsionsystem 100 may be referred to as a hybrid electric vehicle (HEV).

Vehicle propulsion system 100 may utilize a variety of differentoperational modes depending on operating conditions encountered by thevehicle propulsion system. Some of these modes may enable engine 110 tobe maintained in an off state (i.e. set to a deactivated state) wherecombustion of fuel at the engine is discontinued. For example, underselect operating conditions, motor 120 may propel the vehicle via drivewheel 130 as indicated by arrow 123 while engine 110 is deactivated.

During other operating conditions, engine 110 may be set to adeactivated state (as described above) while motor 120 may be operatedto charge energy storage device 150. For example, motor 120 may receivewheel torque from drive wheel 130 as indicated by arrow 122 where themotor may convert the kinetic energy of the vehicle to electrical energyfor storage at energy storage device 150 as indicated by arrow 124. Thisoperation may be referred to as regenerative braking of the vehicle.Thus, motor 120 can provide a generator function in some embodiments.However, in other embodiments, generator 160 may instead receive wheeltorque from drive wheel 130, where the generator may convert the kineticenergy of the vehicle to electrical energy for storage at energy storagedevice 150 as indicated by arrow 162.

During still other operating conditions, engine 110 may be operated bycombusting fuel received from fuel system 140 as indicated by arrow 142.For example, engine 110 may be operated to propel the vehicle via drivewheel 130 as indicated by arrow 121 while motor 120 is deactivated.During other operating conditions, both engine 110 and motor 120 mayeach be operated to propel the vehicle via drive wheel 130 as indicatedby arrows 121 and 123, respectively. A configuration where both theengine and the motor may selectively propel the vehicle may be referredto as a parallel type vehicle propulsion system. Note that in someembodiments, motor 120 may propel the vehicle via a first set of drivewheels and engine 110 may propel the vehicle via a second set of drivewheels.

In other embodiments, vehicle propulsion system 100 may be configured asa series type vehicle propulsion system, whereby the engine does notdirectly propel the drive wheels. Rather, engine 110 may be operated topower motor 120, which may in turn propel the vehicle via drive wheel130 as indicated by arrow 122. For example, during select operatingconditions, engine 110 may drive generator 160, as indicated by arrow116, which may in turn supply electrical energy to one or more of motor120 as indicated by arrow 141 or energy storage device 150 as indicatedby arrow 162. As another example, engine 110 may be operated to drivemotor 120 which may in turn provide a generator function to convert theengine output to electrical energy, where the electrical energy may bestored at energy storage device 150 for later use by the motor.

Fuel system 140 may include one or more fuel storage tanks 143 forstoring fuel on-board the vehicle. For example, fuel tank 143 may storeone or more liquid fuels, including but not limited to: gasoline,diesel, and alcohol fuels. In some examples, the fuel may be storedon-board the vehicle as a blend of two or more different fuels. Forexample, fuel tank 143 may be configured to store a blend of gasolineand ethanol (e.g., E10, E85, etc.) or a blend of gasoline and methanol(e.g., M10, M85, etc.), whereby these fuels or fuel blends may bedelivered to engine 110 as indicated by arrow 142. Still other suitablefuels or fuel blends may be supplied to engine 110, where they may becombusted at the engine to produce an engine output. The engine outputmay be utilized to propel the vehicle as indicated by arrow 121 or torecharge energy storage device 150 via motor 120 or generator 160.

In some embodiments, energy storage device 150 may be configured tostore electrical energy that may be supplied to other electrical loadsresiding on-board the vehicle (other than the motor), including cabinheating and air conditioning, engine starting, headlights, cabin audioand video systems, etc. As a non-limiting example, energy storage device150 may include one or more batteries and/or capacitors.

Vehicle propulsion system 100 may include a heating ventilation and airconditioning (HVAC) system (not shown). The HVAC system may include anevaporator for cooling vehicle cabin air. Air may be passed over theevaporator via a fan and directed around the vehicle cabin. A climatecontroller (not shown) may operate the fan according to operatorsettings (received via an operator interface) as well as climatesensors. Further, the climate controller may operate the fan based on anumber of occupants sensed within the vehicle. An evaporator temperaturesensor (not shown) may provide an indication of the temperature ofevaporator to the climate controller. A cabin temperature sensor mayprovide an indication of cabin temperature to the climate controller.The climate controller may also receive operator inputs from an operatorinterface and supply desired evaporator temperature and actualevaporator temperature to control system 190. The operator interface mayallow an operator to select a desired cabin temperature, fan speed, anddistribution path for conditioned cabin air. In one example, responsiveto an occupancy level of the vehicle being lower (such as when there areno occupants in the vehicle, or when the occupant(s) is a passengerrather than a driver, a controller of the control system 190 mayincrease a desired air conditioning set point, or shut-off the HVACsystem so as to reduce the amount of accessory load applied on theengine. Optionally, the controller may lower the desired airconditioning set point or enable the HVAC system when an occupant ispicked up (such as when nearing a passenger pick-up location) or when adriver is detected in the vehicle.

Control system 190 may communicate with one or more of engine 110, motor120, fuel system 140, energy storage device 150, and generator 160. Forexample, control system 190 may receive sensory feedback informationfrom one or more of engine 110, motor 120, fuel system 140, energystorage device 150, and generator 160. Further, control system 190 maysend control signals to one or more of engine 110, motor 120, fuelsystem 140, energy storage device 150, and generator 160 responsive tothis sensory feedback. Control system 190 may receive an indication ofan operator requested output of the vehicle propulsion system from avehicle operator 102. For example, control system 190 may receivesensory feedback from pedal position sensor 194 which communicates withpedal 192. Pedal 192 may refer schematically to a brake pedal and/or anaccelerator pedal. Furthermore, in some examples control system 190 maybe in communication with a remote engine start receiver 195 (ortransceiver) that receives wireless signals 106 from a key fob 111having a remote start button 105. In other examples (not shown), aremote engine start may be initiated via a cellular telephone, orsmartphone based system where a user's cellular telephone sends data toa server and the server communicates with the vehicle to start theengine.

Further, control system 190 may include an autonomous driving module 191that comprises instructions for autonomously and/or semi-autonomously,i.e., wholly or partially without operator input, operating the vehiclepropulsion system 100. The vehicle propulsion system 100 may furtherinclude autonomous driving sensors 193 and an autonomous controllerwithin the module that receives signals generated by the autonomousdriving sensors (e.g., sensors for driving the vehicle in an autonomousmode) and controls at least one vehicle subsystem to operate the vehiclein autonomous mode according to the signals received. The autonomoussensors 193 may include any number of devices configured to generatesignals that help navigate the vehicle propulsion system 100 whileoperating in an autonomous mode. Examples of autonomous sensors 193 mayinclude a radar sensor, a lidar sensor, a camera, or the like. Theautonomous sensors 193 help the vehicle propulsion system 100 “see” theroadway and/or various obstacles while operating in the autonomous mode.

The autonomous mode controller may be configured to control one or moresubsystems while the vehicle propulsion system is operating in theautonomous mode. Examples of subsystems that may be controlled by theautonomous mode controller may include a brake subsystem, a suspensionsubsystem, a steering subsystem, a HVAC subsystem, and a powertrainsubsystem. The autonomous mode controller may control any one or more ofthese subsystems by outputting signals to control units associated withthese subsystems.

While a vehicle is operated in the autonomous mode, vehicle occupantsmay have varying degrees of interaction with the vehicle. For example,the vehicle may have no occupants. As another example, the vehicleoccupant(s) may be a passenger seated in a rear location, and notinteracting with any steering or braking controls of the vehicle. As yetanother example, the vehicle occupant may be a passive driver seated ina front location, and not interacting with any steering or brakingcontrols of the vehicle. In both these cases, the vehicle controllerprovides command signals for driving the vehicle, and the vehicle isoperated with a higher degree of autonomous driving. As still anotherexample, the vehicle occupant may be an active driver seated interactingwith one or more of the steering and braking controls of the vehicle.Based on the level of interaction, the degree of autonomous drivingprovided via the controller may be varied.

Energy storage device 150 may periodically receive electrical energyfrom a power source 180 residing external to the vehicle (e.g., not partof the vehicle) as indicated by arrow 184. As a non-limiting example,vehicle propulsion system 100 may be configured as a plug-in hybridelectric vehicle (PHEV), whereby electrical energy may be supplied toenergy storage device 150 from power source 180 via an electrical energytransmission cable 182. During a recharging operation of energy storagedevice 150 from power source 180, electrical transmission cable 182 mayelectrically couple energy storage device 150 and power source 180.While the vehicle propulsion system is operated to propel the vehicle,electrical transmission cable 182 may be disconnected between powersource 180 and energy storage device 150. Control system 190 mayidentify and/or control the amount of electrical energy stored at theenergy storage device, which may be referred to as the state of charge(SOC).

In other embodiments, electrical transmission cable 182 may be omitted,where electrical energy may be received wirelessly at energy storagedevice 150 from power source 180. For example, energy storage device 150may receive electrical energy from power source 180 via one or more ofelectromagnetic induction, radio waves, and electromagnetic resonance.As such, it should be appreciated that any suitable approach may be usedfor recharging energy storage device 150 from a power source that doesnot comprise part of the vehicle. In this way, motor 120 may propel thevehicle by utilizing an energy source other than the fuel utilized byengine 110.

Fuel system 140 may periodically receive fuel from a fuel sourceresiding external to the vehicle. As a non-limiting example, vehiclepropulsion system 100 may be refueled by receiving fuel via a fueldispensing device 170 as indicated by arrow 172. In some embodiments,fuel tank 143 may be configured to store the fuel received from fueldispensing device 170 until it is supplied to engine 110 for combustion.In some embodiments, control system 190 may receive an indication of thelevel of fuel stored at fuel tank 143 via a fuel level sensor. The levelof fuel stored at fuel tank 143 (e.g., as identified by the fuel levelsensor) may be communicated to the vehicle operator, for example, via afuel gauge or indication in a vehicle instrument panel 196.

The vehicle propulsion system 100 may also include an ambienttemperature/humidity sensor 198, and sensors dedicated to indicating theoccupancy-state of the vehicle, for example seat load cells 107, doorsensing technology 108, onboard cameras 109, and microphones. In someexamples, sensors dedicated to indicating occupancy-state of the vehiclemay include including one or more of a thermal imaging system includingan infra-red camera, and a seat sensing system including one or moreseat pressure sensors coupled to each vehicle seat, capacitive touchsensors, and/or infrared eye or face sensors. As elaborated withreference to FIG. 4, vehicle occupancy may also be inferred based onvehicle mass estimates, a priori modus operandi via cloud dispatch orV2V or V2X communications, as well as inputs from accelerator, brake,steering, and range inputs. Vehicle propulsion system 100 may alsoinclude inertial sensors 199. Inertial sensors may comprise one or moreof the following: longitudinal, latitudinal, vertical, yaw, roll, andpitch sensors. The vehicle instrument panel 196 may include indicatorlight(s) and/or a text-based display in which messages are displayed toan operator. The vehicle instrument panel 196 may also include variousinput portions for receiving an operator input, such as buttons, touchscreens, voice input/recognition, etc. For example, the vehicleinstrument panel 196 may include a refueling button 197 which may bemanually actuated or pressed by a vehicle operator to initiaterefueling. For example, in response to the vehicle operator actuatingrefueling button 197, a fuel tank in the vehicle may be depressurized sothat refueling may be performed.

In an alternative embodiment, the vehicle instrument panel 196 maycommunicate audio messages to the operator without display. Further, thesensor(s) 199 may include a vertical accelerometer to indicate roadroughness. These devices may be connected to control system 190. In oneexample, the control system may adjust engine output and/or the wheelbrakes to increase vehicle stability in response to sensor(s) 199.

Further, in some embodiments, the vehicle instrument panel 196 mayinclude an interface for indicating an occupancy-based mode of vehicleoperation. For example, the vehicle occupancy level may dictate apreference for fuel economy over NVH, or vice-versa. Alternatively, thedriver may actively select a preference via the interface. As elaboratedwith reference to FIG. 3, powertrain calibration settings may beselected based on the determined occupancy level of the vehicle to biasthe settings towards fuel economy when the occupancy level is lower.Therein, the control unit 190 may reduce NVH constraints, and adjust oneor more actuators of the vehicle to control vehicle operation to improvefuel economy. In comparison, the vehicle settings may be biased towardsNVH when the occupancy level is higher. Therein the control unit 190 mayutilize nominal NVH constraints, and adjust one or more actuators of thevehicle to control vehicle operation to improve drivability and occupantcomfort.

The control unit 190 may adjust vehicle operation based on occupancylevel in the vehicle, including a number of occupants, nature of theoccupants (e.g., driver or passenger), as well as activity level of theoccupant (e.g., whether they are interacting with steering and brakingcontrols or not), as described below with respect to FIGS. 3-12.Specifically, when a lower occupancy level is detected within thevehicle (based on indications from the sensors 107, 108, and 109indicating an occupancy state of the vehicle), the control unit 190 mayadjust one or more vehicle operating parameters to adjust a balancebetween fuel economy and NVH, such that fuel economy improvement isfavored over drivability. For example, when zero occupants are detected,when the occupant is a passenger, or when the driver is a passivedriver, fewer NVH constraints may be applied (e.g., no NVH constraintsmay be applied). Therein, vehicle operation may be adjusted forimproving fuel economy while compromising NVH as NVH will not drivecustomer complaints through interaction with the occupant. In this way,by utilizing occupancy level information, the control unit may adjustvehicle operation to allow NVH excitations from the vehicle powertrain,and increase fuel economy. Details of adjusting one or more vehicleoperating parameters based on lower occupancy levels are furtherelaborated below with respect to FIGS. 3-12. The methods and systemsdescribed herein provide the technical result of improved fuel economyvia reduction of NVH constraints during conditions when NVH constraintsare not likely to disturb vehicle occupants.

Continuing to FIG. 1B, a schematic diagram showing one cylinder of amulti-cylinder engine 10 in an engine system 125, which may be includedin a propulsion system of an vehicle, such as vehicle propulsion system100 at FIG. 1A, is shown. The engine 10 may be an example of engine 110at FIG. 1A. The engine 10 may be controlled at least partially by acontrol system including a controller 12 and by input from a vehicleoperator 132 via an input device 131. In this example, the input device131 includes an accelerator pedal and a pedal position sensor 134 forgenerating a proportional pedal position signal.

In some embodiments, during an autonomous mode of vehicle operation, theengine 10 may be controlled at least partially by the control system viainstructions stored in the controller 12 (alternatively, an autonomouscontroller (not shown) may control the engine during the autonomousmode) and by input from one or more autonomous sensors 189. Examples ofautonomous sensors 189 may include a radar sensor, a lidar sensor, acamera, or the like.

A combustion chamber 30 of the engine 10 may include a cylinder formedby cylinder walls 32 with a piston 36 positioned therein. The piston 36may be coupled to a crankshaft 40 so that reciprocating motion of thepiston is translated into rotational motion of the crankshaft. Thecrankshaft 40 may be coupled to at least one drive wheel of a vehiclevia an intermediate transmission system. Further, a starter motor may becoupled to the crankshaft 40 via a flywheel to enable a startingoperation of the engine 10.

The combustion chamber 30 may receive intake air from an intake manifold44 via an intake passage 42 and may exhaust combustion gases via anexhaust passage 48. The intake manifold 44 and the exhaust passage 48can selectively communicate with the combustion chamber 30 viarespective intake valve 52 and exhaust valve 54. In some examples, thecombustion chamber 30 may include two or more intake valves and/or twoor more exhaust valves.

In this example, the intake valve 52 and exhaust valve 54 may becontrolled by cam actuation via respective cam actuation systems 51 and53. The cam actuation systems 51 and 53 may each include one or morecams and may utilize one or more of cam profile switching (CPS),variable cam timing (VCT), variable valve timing (VVT), and/or variablevalve lift (VVL) systems that may be operated by the controller 12 tovary valve operation. The position of the intake valve 52 and exhaustvalve 54 may be determined by position sensors 55 and 57, respectively.In alternative examples, the intake valve 52 and/or exhaust valve 54 maybe controlled by electric valve actuation. For example, the cylinder 30may alternatively include an intake valve controlled via electric valveactuation and an exhaust valve controlled via cam actuation includingCPS and/or VCT systems.

A fuel injector 69 is shown coupled directly to combustion chamber 30for injecting fuel directly therein in proportion to the pulse width ofa signal received from the controller 12. In this manner, the fuelinjector 69 provides what is known as direct injection of fuel into thecombustion chamber 30. The fuel injector may be mounted in the side ofthe combustion chamber or in the top of the combustion chamber, forexample. Fuel may be delivered to the fuel injector 69 by a fuel system(not shown) including a fuel tank, a fuel pump, and a fuel rail. In someexamples, the combustion chamber 30 may alternatively or additionallyinclude a fuel injector arranged in the intake manifold 44 in aconfiguration that provides what is known as port injection of fuel intothe intake port upstream of the combustion chamber 30.

Spark is provided to combustion chamber 30 via spark plug 66. Theignition system may further comprise an ignition coil (not shown) forincreasing voltage supplied to spark plug 66. In other examples, such asa diesel, spark plug 66 may be omitted.

The engine 10 may operate in various modes. For example, the controller12 may deactivate various numbers of cylinders, such as one cylinder ora plurality of cylinders, and operate the engine with the rest of thecylinders that remain active. In the embodiment illustrated in FIG. 1B,actuation systems for the intake valves 52 and exhaust valves 54 asdescribed above may control valve opening and closing, which can be usedto provide one or more reduced displacement operating modes with one ormore cylinders deactivated and not combusting fuel. As used herein, areduced displacement mode includes an engine operating mode where one ormore cylinders do not combust fuel to power the crankshaft whiledeactivated. During the reduced or variable displacement operatingmodes, one or more cylinders may be deactivated by modifying ordisabling operation of the intake valves, exhaust valves, or both incombination with cutting off fuel provided to the deactivated cylinders.

The intake passage 42 may include a throttle 62 having a throttle plate64. In this particular example, the position of throttle plate 64 may bevaried by the controller 12 via a signal provided to an electric motoror actuator included with the throttle 62, a configuration that iscommonly referred to as electronic throttle control (ETC). In thismanner, the throttle 62 may be operated to vary the intake air providedto the combustion chamber 30 among other engine cylinders. The positionof the throttle plate 64 may be provided to the controller 12 by athrottle position signal. The intake passage 42 may include a mass airflow sensor 120 and a manifold air pressure sensor 122 for sensing anamount of air entering engine 10.

An exhaust gas sensor 126 is shown coupled to the exhaust passage 48upstream of an emission control device 70 according to a direction ofexhaust flow. The sensor 126 may be any suitable sensor for providing anindication of exhaust gas air-fuel ratio such as a linear oxygen sensoror UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygensensor or EGO, a HEGO (heated EGO), a NO_(x), HC, or CO sensor. In oneexample, upstream exhaust gas sensor 126 is a UEGO configured to provideoutput, such as a voltage signal, that is proportional to the amount ofoxygen present in the exhaust. Controller 12 converts oxygen sensoroutput into exhaust gas air-fuel ratio via an oxygen sensor transferfunction.

The emission control device 70 is shown arranged along the exhaustpassage 48 downstream of the exhaust gas sensor 126. The device 70 maybe a three way catalyst (TWC), NOR trap, various other emission controldevices, or combinations thereof. In some examples, during operation ofthe engine 10, the emission control device 70 may be periodically resetby operating at least one cylinder of the engine within a particularair-fuel ratio.

An exhaust gas recirculation (EGR) system 139 may route a desiredportion of exhaust gas from the exhaust passage 48 to the intakemanifold 44 via an EGR passage 152. The amount of EGR provided to theintake manifold 44 may be varied by the controller 12 via an EGR valve144. Under some conditions, the EGR system 139 may be used to regulatethe temperature of the air-fuel mixture within the combustion chamber,thus providing a method of controlling the timing of ignition duringsome combustion modes.

The controller 12 is shown in FIG. 1B as a microcomputer, including amicroprocessor unit 102, input/output ports 104, an electronic storagemedium for executable programs and calibration values shown as read onlymemory chip 106 (e.g., non-transitory memory) in this particularexample, random access memory 113, keep alive memory 115, and a databus. The controller 12 may receive various signals from sensors coupledto the engine 10, in addition to those signals previously discussed,including measurement of inducted mass air flow (MAF) from the mass airflow sensor 129; engine coolant temperature (ECT) from a temperaturesensor 112 coupled to a cooling sleeve 114; an engine position signalfrom a Hall effect sensor 118 (or other type) sensing a position ofcrankshaft 40; throttle position from a throttle position sensor 65; andmanifold absolute pressure (MAP) signal from the sensor 122. An enginespeed signal may be generated by the controller 12 from crankshaftposition sensor 118. Manifold pressure signal also provides anindication of vacuum, or pressure, in the intake manifold 44. Note thatvarious combinations of the above sensors may be used, such as a MAFsensor without a MAP sensor, or vice versa. During engine operation,engine torque may be inferred from the output of MAP sensor 122 andengine speed. Further, this sensor, along with the detected enginespeed, may be a basis for estimating charge (including air) inductedinto the cylinder. In one example, the crankshaft position sensor 118,which is also used as an engine speed sensor, may produce apredetermined number of equally spaced pulses every revolution of thecrankshaft.

The storage medium read-only memory 106 can be programmed with computerreadable data representing non-transitory instructions executable by theprocessor 102 for performing the methods described below as well asother variants that are anticipated but not specifically listed.

During operation, each cylinder within engine 10 typically undergoes afour stroke cycle: the cycle includes the intake stroke, compressionstroke, expansion stroke, and exhaust stroke. During the intake stroke,generally, the exhaust valve 54 closes and intake valve 52 opens. Air isintroduced into combustion chamber 30 via intake manifold 44, and piston36 moves to the bottom of the cylinder so as to increase the volumewithin combustion chamber 30. The position at which piston 36 is nearthe bottom of the cylinder and at the end of its stroke (e.g., whencombustion chamber 30 is at its largest volume) is typically referred toby those of skill in the art as bottom dead center (BDC).

During the compression stroke, intake valve 52 and exhaust valve 54 areclosed. Piston 36 moves toward the cylinder head so as to compress theair within combustion chamber 30. The point at which piston 36 is at theend of its stroke and closest to the cylinder head (e.g., whencombustion chamber 30 is at its smallest volume) is typically referredto by those of skill in the art as top dead center (TDC). In a processhereinafter referred to as injection, fuel is introduced into thecombustion chamber. In a process hereinafter referred to as ignition,the injected fuel is ignited by known ignition means such as spark plug92, resulting in combustion.

During the expansion stroke, the expanding gases push piston 36 back toBDC. Crankshaft 40 converts piston movement into a rotational torque ofthe rotary shaft. Finally, during the exhaust stroke, the exhaust valve54 opens to release the combusted air-fuel mixture to exhaust manifold48 and the piston returns to TDC. Note that the above is shown merely asan example, and that intake and exhaust valve opening and/or closingtimings may vary, such as to provide positive or negative valve overlap,late intake valve closing, or various other examples.

In some embodiments, during an autonomous mode of vehicle operation, theengine 10 may be autonomously controlled by the controller 12 based onsignals received from autonomous sensors, such as autonomous sensorsdescribed with respect to FIG. 1A. In some examples, an autonomouscontroller within the control module may control engine operation duringthe autonomous mode.

As described above, FIG. 1B shows only one cylinder of a multi-cylinderengine, and each cylinder may similarly include its own set ofintake/exhaust valves, fuel injector, spark plug, etc.

As will be appreciated by someone skilled in the art, the specificroutines described below in the flowcharts may represent one or more ofany number of processing strategies such as event driven,interrupt-driven, multi-tasking, multi-threading, and the like. As such,various acts or functions illustrated may be performed in the sequenceillustrated, in parallel, or in some cases omitted. Like, the order ofprocessing is not necessarily required to achieve the features andadvantages, but is provided for ease of illustration and description.Although not explicitly illustrated, one or more of the illustrated actsor functions may be repeatedly performed depending on the particularstrategy being used. Further, these figures graphically represent codeto be programmed into the computer readable storage medium in controller12 to be carried out by the controller in combination with the enginehardware, as illustrated in FIG. 1B.

FIG. 2 is a block diagram of a vehicle drive-train 200. Drive-train 200may be powered by engine 10. Engine 10 is described with respect to FIG.1B. Drive train 200 may be included a vehicle propulsion system, such asvehicle propulsion system 100 in FIG. 1A. In one example, engine 10 maybe a gasoline engine. In alternate examples, other engine configurationsmay be employed, for example, a diesel engine. Engine 10 may be startedwith an engine starting system (not shown). Further, engine 10 maygenerate or adjust torque via torque actuator 204, such as a fuelinjector, throttle, etc.

An engine output torque may be transmitted to torque converter 206 todrive an automatic transmission 208 by engaging one or more clutches,including forward clutch 210, where the torque converter may be referredto as a component of the transmission. Torque converter 206 includes animpeller 220 that transmits torque to turbine 222 via hydraulic fluid.One or more clutches may be engaged to change mechanical advantagebetween the engine vehicle wheels 214. Impeller speed may be determinedvia speed sensor 225, and turbine speed may be determined from speedsensor 226 or from vehicle speed sensor 230. The output of the torqueconverter may in turn be controlled by torque converter lock-up clutch212. As such, when torque converter lock-up clutch 212 is fullydisengaged, torque converter 206 transmits torque to automatictransmission 208 via fluid transfer between the torque converter turbineand torque converter impeller, thereby enabling torque multiplication.In contrast, when torque converter lock-up clutch 212 is fully engaged,the engine output torque is directly transferred via the torqueconverter clutch to an input shaft (not shown) of transmission 208.Alternatively, the torque converter lock-up clutch 212 may be partiallyengaged, thereby enabling the amount of torque relayed to thetransmission to be adjusted. Although one lock-up clutch 212 isprovided, the torque converter 206 may also contain more than onelock-up clutches. The lock-up clutch 212 may be of various types thatcan allow various states of engagements between the pump impeller 220and the turbine 222, such as a wet-type friction clutch, by for exampleproviding various degrees of slip between the pump impeller 220 and theturbine 222. The lock-up clutch may be electronically control via anelectromechanical actuator, electro-hydraulic actuator, etc.

As described with respect to FIG. 1B, engine 10 may be controlled bycontroller 12. Controller 12 may be configured to adjust the amount oftorque transmitted by the torque converter by adjusting the torqueconverter lock-up clutch in response to various engine operatingconditions, or based on a driver-based engine operation request. Thecontroller 12 may also control the operation of the lock-up clutch 212through a lock-up clutch actuator (not shown). For example, thecontroller 12 may sense a vehicle operating condition (e.g., through thevarious sensors and actuators, such as those described with respect toFIGS. 1A and 1B), calculates a target lock-up clutch engagementpressure, which corresponds to a target engagement state for the pumpimpeller 220 and the turbine 22, and then sends signals to the lock-upclutch actuator to cause the lock-up clutch 212 to apply the targetengagement pressure to the pump impeller 220 and turbine runner 222.

The engagement state between the pump impeller 220 and the turbine 222may depend on the lock-up clutch engagement pressure applied. Forexample, if the engagement pressure (PEN) is at or above a thresholdvalue (PA), or PEN≥PA, the pump impeller 220 and turbine 222 becomefully engaged, that is they move as an integral part; if the engagementpressure is at or below a threshold value PB, the pump impeller 220 andthe turbine 222 become completely disengaged, leaving only a fluidcoupling between the pump impeller 220 and the turbine 222; and if theengagement pressure is between threshold values PA and PB the pumpimpeller 220 and the turbine 222 become partially engaged, allowing someslip between the pump impeller 220 and the turbine runner 222, and theslip decreases with an increase in the engagement pressure.

For example, a slip of 0% occurs when the pump impeller 220 and theturbine 222 are fully engaged and moves as an integral part. A slip of100% indicates that there is a complete fluid coupling and no mechanicalengagement between the pump impeller 220 and the turbine 222. A slipbetween 0 to 100% indicates that the pump impeller and the turbinerunner are partially mechanically engaged and there is some slip betweenthem. As the slip decreases, the engagement between the pump impeller220 and the turbine 222 increases.

Torque output from the automatic transmission 208 may in turn be relayedto wheels 214 to propel the vehicle. Specifically, automatictransmission 208 may adjust an input driving torque at the input shaft(not shown) responsive to a vehicle traveling condition beforetransmitting an output driving torque to the wheels.

Further, wheels 214 may be locked by engaging wheel brakes 216. In oneexample, wheel brakes 216 may be engaged in response to the driverpressing his foot on a brake pedal (not shown). In the similar way,wheels 214 may be unlocked by disengaging wheel brakes 216 in responseto the driver releasing his foot from the brake pedal. During anautonomous mode of engine operation, brakes may be engaged or disengagedbased on indication from one or more autonomous sensors.

A mechanical oil pump (not shown) may be in fluid communication withautomatic transmission 208 to provide hydraulic pressure to engagevarious clutches, such as forward clutch 210 and/or torque converterlock-up clutch 212. The mechanical oil pump may be operated inaccordance with torque converter 206, and may be driven by the rotationof the engine or transmission input shaft, for example. Thus, thehydraulic pressure generated in mechanical oil pump may increase as anengine speed increases, and may decrease as an engine speed decreases.

In one example, torque converter operation may be adjusted based on adetected occupancy level in the vehicle. For example, when the occupancylevel is lower, the controller may apply reduced NVH constraints toimprove fuel economy as concern for NVH is decreased. Accordingly, thecontroller may adjust a torque converter slip towards less slip. In someexamples, the controller may utilize a look-up table based on reducedNVH constraints to determine a desired torque converter slip and adjustthe torque converter actuator to provide the desired slip. For a givenengine speed and load, the desired torque converter slip may decrease asthe occupancy level decreases. By decreasing the torque converter slipwhen the occupancy level is lower, fuel economy may be improved byreducing torque loss during conversion while NVH may increase due toless dampening effect. However, concern for NVH may be lower due to thelower occupancy level and torque converter operation may be adjusted forimproving fuel economy over NVH. In some examples, torque converteroperation may also be adjusted based on an operator selected setting (ormode) for a preference between fuel economy and NVH.

In this way, torque converter operation may be adjusted based onoccupancy level to provide greater fuel economy benefits. Additionally,various vehicle operations, such as VDE, EGR, DFSO, idle, etc., may beadjusted based on the number of occupants detected within the vehicle.Details of adjusting the various vehicle operations based on the numberof occupants to improve fuel economy will be further elaborated withrespect to FIGS. 3-12 below.

Turning to FIG. 3, a flow chart is shown illustrating an example method300 for adjusting vehicle operation based on an occupancy level of avehicle. Specifically, method 300 includes adjusting vehicle operationby lowering NVH constraints to improve fuel economy when the vehicle isoperating in an autonomous mode and the occupancy level is lower (e.g.,lower than a threshold) in the vehicle. Instructions for carrying outmethod 300 and other methods included herein may be executed by acontroller of the vehicle system, such as controller 12 at FIGS. 1A, 1B,and 2, based on instructions stored in non-transitory memory of thecontroller, and in conjunction with signals received from sensors of thevehicle system, such as the sensors described above with reference toFIGS. 1A, 1B, and 2. The controller may employ actuators of the vehiclesystem, such as the actuators described with reference to FIGS. 1A, 1B,and 2, to adjust vehicle operation based on a number of occupants,whether the occupant is a passenger or a driver, and if the driver isactive or passive in vehicle control. The adjustments enable vehicleoperation to be controlled to increase fuel economy while reducing NVHconstraints as the occupancy level decreases, according to the methodsdescribed below.

Method 300 begins at 302. At 302, method 300 includes evaluating vehicleoperating conditions. Vehicle operating conditions may include a mode ofvehicle operation (e.g., autonomous, semi-autonomous, or operated by anoperator), ambient conditions, engine operating conditions, heatingventilation and air conditioning (HVAC) conditions, and fuel systemoperating conditions. Engine operating conditions may include engineload, engine speed, mode of engine operation (e.g., VDE or non-VDE),exhaust gas recirculation parameters, amount of throttle valve opening,engine temperature, spark timing, transmission gear ratio, and exhaustcatalyst temperature. Fuel system operating conditions may includerefueling conditions, fuel tank pressure, fuel tank temperature, fuelpump operating conditions, fuel system diagnostic conditions, andevaporative emissions system conditions. Ambient conditions may includeambient humidity, ambient temperature, and ambient pressure. HVACconditions may include air conditioning system status, air conditioningclutch voltage, condenser fan speed, and cabin temperature. Evaluatingvehicle operating conditions may also include evaluating road conditionduring vehicle operation. Road conditions may include road roughness,and inclination, as well as weather conditions (e.g., precipitation,snow, etc.). Vehicle operating conditions may be estimated and/ormeasured by utilizing one or more sensors of the vehicle system, such assensors described with respect to FIGS. 1A, 1B, and 2.

Next, method 300 proceeds to 304. At 304, method 300 includesdetermining if the vehicle is operating in an autonomous mode. In oneexample, the vehicle may be operating in an autonomous mode if anautonomous mode is selected by a vehicle operator, such as via remotecommunication. If the vehicle is operating in an autonomous mode, theanswer at 304 is NO, and method 300 proceeds to 310. At 310, method 300includes operating the vehicle based on nominal NVH constraints. Forexample, when the vehicle is not operating in the autonomous mode, avehicle operator is controlling the operation of the vehicle. Therefore,one or more parameters of vehicle operation may be adjusted such thatimpact of noise, vibration, and harshness (NVH) experienced by theoperator, and any occupants in the vehicle, are reduced and drivabilityis improved. As such, this may result in the powertrain calibrationsettings to be biased away from a theoretical ideal setting for fueleconomy due to the imposition of NVH constraints. The degree of NVHconstraints applied may be at a highest setting when the vehicle is notoperating in the autonomous mode.

The one or more parameters of the vehicle operation that are adjustedwith NVH constraints applied may include EGR operation. For example, anamount of EGR delivered may be limited based on NVH constraints. In oneexample, during idle conditions, when nominal NVH constraints are used,EGR may not be delivered (that is desired EGR may be zero) in order toreduce idle roughness when engine is operating at idle speed and load.In another example, when nominal NVH constraints are used, during roughroad conditions (that is, when the vehicle is travelling on rough road),EGR may be disabled to reduce NVH and improve drivability. In yetanother example, in vehicles equipped with an EGR cooler, when nominalNVH constraints are applied, during cold start conditions, EGR may bedisabled for a threshold duration after light-off until a desired EGRcooler temperature is reached. Delaying EGR after catalyst light-offprovides reduced NVH and increases drivability.

As another example, idle operation may be adjusted to reduce NVH. Forexample, when the engine is operating at idle conditions, a VDE mode ofoperation may be disabled, and an amount of spark retard may be limitedbased on NVH constraints.

As another example, VDE mode of operation may be adjusted. For example,during VDE conditions, a number of cylinders deactivated may be reducedto reduce NVH. That is, the number of cylinders that may be deactivatedin the VDE may be based on nominal NVH constraints for improveddrivability.

As yet another example, a torque converter slip rate may be adjusted.For example, when a lock-up clutch is locked (lock-up mode), a directconnection is provided between the engine and transmission, whichincreases efficiency. However, in the lock-up mode, due to mechanicalcoupling via the lock-up clutch, drivetrain noise and vibration isexperienced by the operator and/or occupants in the vehicle. In order toprovide improved drivability, the torque converter may be allowed toslip, thereby increasing fluidic coupling and decreasing mechanicalcoupling. The fluidic coupling dampens the sensitivity to drivetrainvibration, thereby improving NVH performance. An amount of slip may bebased on drivetrain resonance for a given engine speed. Specifically,the amount of slip may be determined based on a torque converter slipschedule or map stored in a memory of a controller. The map may be usedto determine the desired torque converter slip that provides desireddampening effect for the current engine load and speed. The controllermay then adjust a torque converter actuator to provide the desired slip.

As a further example, a lugging NVH limit may be based on nominal NVHconstraints. For example, at lower engine speeds, if a torque converterslip is reduced below a threshold torque converter slip (e.g., 30 rpm orlower), the vehicle would fail to meet the desired NVH target fordrivability. Specifically, an NVH mode known as lugging caused byimpulsive inputs due to delivering high combustion torques can beinduced if too much torque is requested at low engine speeds when thegear ratio is too high. A torque converter may be used to control NVHassociated with lugging. Specifically, slipping the torque converterincreases damping. As a result, sensitivity of driveline vibrations toengine torque excitation is reduced, which improves NVH. Thus, duringlugging conditions, vehicle may be operated with a torque converter slipabove a threshold torque converter slip in order to meet desired NVHlevel and maintain drivability. In other words, torque converteroperation is adjusted such that desired NVH levels are maintained duringlugging.

As still another example, a transmission shift schedule for improved NVHmay be used. For example, Upshift and Downshift decisions may be basedon the maximum torque available at any given time to ensure gooddrivability and good NVH.

As a further example, DFSO operation may be adjusted. Specifically, atransition into and out of DFSO may be adjusted. For example, when DFSOconditions are met, deactivation of fuel injectors to all cylinders maybe delayed. Further, in order to improve NVH, activation of fuelinjectors may be performed earlier, responsive to brake release andvehicle speed greater than a threshold speed. Further, DFSO may bedisabled under low gear operation, and all-wheel drive operation.

As a still further example, operation of a solenoid valve of a HP pumpmay be adjusted to reduce NVH during low speed engine operation.Furthermore, in some examples, air conditioning compressor clutchcycling may be adjusted for reduced NVH.

Returning to 304, if the vehicle is operating in an autonomous mode, theanswer at 304 is YES, and method 300 proceeds to 306. At 306, method 300includes determining an occupancy level of the vehicle. As elaboratedwith reference to FIG. 4, determining the occupancy level includesdetermining a number of occupants in the vehicle, determining if theoccupant is a driver or a passenger, and if a driver is present, thendetermining if the driver is actively involved in vehicle control ornot. The occupancy level may be determined based on one or more of aseat pressure sensor, an infra-red sensor, one or more cameras andmicrophones to identify occupants within the vehicle, etc.

At 308, the method includes selecting vehicle parameter calibrationsettings based on determined occupancy level. At 310, the selectingincludes operating the vehicle based on reduced NVH constraints forimproved fuel economy. Therein, progressively lower NVH constraints maybe applied, relative to the nominal NVH constraints, as the occupancylevel decreases. By implementing reduced NVH constraints for adjustingone or more vehicle operating parameters, an improvement in fuel economyis achieved.

The one or more parameters of the vehicle operation that are adjustedwith reduced NVH constraints applied may include, at 320, EGR operation,as detailed at FIG. 5. Further, idle operation may be adjusted at 322.For example, the engine idle speed may be lowered to below a nominalidle speed limit that is applied when the vehicle is not operated in theautonomous mode. As an example, when the vehicle occupancy level ishigher (e.g., higher than a threshold, such as may occur when thevehicle includes an active driver and a passenger), an engine idle speedof 400 rpm may be applied. In comparison, when the vehicle includes onlya passive driver, an engine idle speed of lower than 400 rpm may beapplied. Further still, when the vehicle only includes a passenger (andno driver), an engine idle speed further lower of 400 rpm may beapplied.

At 324, VDE operation may be adjusted. Details of adjusting VDEoperation for improved fuel economy by reducing NVH constraints iselaborated at FIGS. 6A and 6B. At 326, a torque converter slip rate maybe adjusted. Details of adjusting torque converter operation forimproved fuel economy by reducing NVH constraints is elaborated at FIG.7. Further, at 328, lugging limits may be adjusted. Details of adjustinglugging limits for improved fuel economy by reducing NVH constraints iselaborated at FIG. 8. Further, at 330, transmission shifting may beadjusted. Details of adjusting transmission shift schedule for improvedfuel economy by reducing NVH constraints are elaborated at FIG. 9.Further, at 332, method 300 includes adjusting DFSO operation byreducing NVH constraints, as elaborated at FIG. 10.

At 334, the method includes adjusting a variable cam timing (VCT) basedon the reduced NVH constraints. For example, when the vehicle occupancylevel is lower (e.g., lower than a threshold), VCT may be positioned totrack maximum fuel efficiency.

At 336, the method includes adjusting accessory loads based on thereduced NVH constraints. For example, HVAC may be set to a highertemperature set point to reduce the accessory load applied on theengine. In one example, as the occupancy level of the vehicle decreases,the temperature set point may be raised relative to a nominal setting,and the accessory load may also correspondingly decrease.

At 338, the method includes adjusting lash mitigation settings based onthe reduced NVH constraints. For example, spark retard usage to managedriveline lash/shuffle may be reduced. In one example, as the occupancylevel of the vehicle decreases, the amount of spark retard applied forlash mitigation may be reduced. As a result, when the occupancy level islowest, lash may not be mitigated since the associated NVH may not beobjectionable to vehicle occupants.

At 340, the method includes adjusting the schedule for on-boarddiagnostics, such as those used for knock, clutch slip, DPFregeneration, etc., based on the reduced NVH constraints. In oneexample, as elaborated at FIG. 11, when the occupancy level is lower,the vehicle controller may intrusively run diagnostic routines and/oradaptive control strategies for knock control, clutch slip, DPFregeneration, etc. As such, these may be diagnostic routines that wouldhave otherwise not been performed due to NVH that is objectionable tothe vehicle operator. In still other examples, entry and exit conditionsfor the OBD routines may be relaxed when the occupancy level is lower.

At 342, the method includes adjusting HEV operation settings based onthe reduced NVH constraints. These adjustments are elaborated at FIG.12. For example, a more aggressive approach may be applied for charginga system battery when operating the hybrid vehicle in an engine mode sothat the vehicle can be operated in an electric mode for a longerduration or a longer distance during a later part of the drive cycle.

In this way, by adjusting vehicle calibration to bias fuel economy overNVH constraints during autonomous vehicle operating conditions when thevehicle's occupancy level is lower, fuel economy may be improved.

In some applications, transmission clutch slippage during shifting alsomay be used and controlled based on the number of occupants. Forexample, transmission clutch slippage during gear shifts may be used toprovide an occupant with a sensation of smoother gear shifts. When anoccupant is not present, transmission clutch slippage may be decreasedto improve fuel economy. Transmission clutch shifting during gear shiftsmay be used in place of, or in addition to, adjusting the torqueconverter lock-up clutch during shifting described with reference toFIG. 9, step 908.

In still further applications, vehicles having stop/start capability maybe controlled during mode transitions between stop and start dependentupon the occupancy level of the vehicle. When the occupancy level islower, a more aggressive engine stopping may be programmed for improvedfuel economy at the cost of more abrupt stops and starts. For example,the vehicle speed at which the engine is shut-off when stopping may beincreased when an occupant is not present for improved fuel economy.Engine stop (also referred to as engine shut-off) may be performed bydeactivating one or more of fuel injection and spark, for example.

Turning to FIG. 4, an example method 400 for determining an occupancylevel of the vehicle is shown. The method of FIG. 4 may be performed aspart of the method of FIG. 3, such as at 306. Method 500 will bedescribed herein with reference to the components and systems depictedin FIGS. 1A, 1B, and 2, though it should be understood that the methodmay be applied to other systems without departing from the scope of thisdisclosure.

At 402, the method includes receiving sensor input indicative ofoccupancy information. This includes input from sensors coupled tovehicle seats, such as seat pressure sensors, occupancy sensors, andcapacitive touch sensors. Input may also be received from cameras andmicrophones coupled to the vehicle cabin. Input may also be receivedfrom infra-red based eye and face sensors. The sensor input may beindicative of a number of occupants as well as their location within thevehicle cabin. For example, the sensor input may indicate if an occupantis present, and if so, if the occupant is a passenger or a driver.

Further still, data may be received from engine system components andengine actuators that are actuated based on input from an operator. Forexample, input may be received from steering and braking systemcomponents. These may include a steering wheel sensor, a brake pedalsensor, an accelerator pedal sensor, etc. The input may indicate if adriver, when present, is actively involved in vehicle control. In someexamples, while a vehicle is in an autonomous mode, a vehicle driver maysit in the driver's seat but let the vehicle controller control allvehicle settings. Alternatively, the vehicle driver may control one ormore of the steering and pedals.

If an occupant is present in the vehicle, and further based on theirseating location and their level of driving activity, the NVH theyexperience during vehicle propulsion may vary. This is because theirseating location and activity level affects the vehicle surfaces theyare in contact with. NVH is transmitted through several vehiclesurfaces, such as through the seat, the steering wheel, the pedals,sound in the cabin, etc. Thus, if an occupant is present in the vehiclein a passenger seat (e.g., in the rear of the vehicle, but not in thedriver seat in the front of the vehicle), the NVH they experience may belimited to NVH transmitted through the cabin and seats. In comparison,if the occupant is a driver, they may experience more NVH due to beingin the front seat, and additional NVH if they actively interacting witha steering control and/or pedals.

It will be appreciated that in addition to sensor input, occupancyinformation may also be inferred based on vehicle mass estimates, apriori modus operandi information, such as received via cloud dispatchor V2X communications, etc.

At 404, it may be determined, based on sensor input, if any occupantsare present. If there are no occupants, then at 406, a first, lowestoccupancy level may be indicated. If any occupant is present, then themethod moves to 408 where it is determined, based on the sensor input,if the occupant (or one of the occupants) is in a driver's seat. If not,then at 410, based on all the occupants being passengers, a secondoccupancy level, higher than the first occupancy level, may beindicated.

If an occupant is present in the driver's seat, then at 412, it may bedetermined if the driver is active. For example, it may be determined ifthe driver is actively interacting with the steering and/or brakingcontrols. As one example, the vehicle may contain a passenger (but notnecessarily a driver), who may be seated in the “driver's seat” but whois not currently driving the vehicle, even if they were driving atanother point in the given drive cycle. In one example, the occupant mayhave actively driven from one point to a highway, and then enabled theautonomous system to take over the driving controls once the vehicle wason the highway. If the occupant in the driver's seat is not currentlydriving the vehicle, then at 414, a third occupancy level, higher thaneach of the first and second occupancy levels, may be indicated.

If the driver is active, then at 416, it may be determined if the driveris actively operating both steering and pedal controls. In one example,the vehicle occupant may be a driver operating steering controls but notpedal controls. In another example, the vehicle occupant may be a driveroperating both steering controls and pedal controls. If the driver isoperating only one of the steering and pedal controls, then at 418, afourth occupancy level, higher than each of the first, second, and thirdoccupancy levels, may be indicated. If the driver is operating both thesteering and pedal controls, then at 420, a fifth, highest occupancylevel may be indicated. In this way, based on the presence of vehicleoccupants, and further based on their seating position within thevehicle cabin, and their inferred level of interaction with vehiclecontrols and actuators, an occupancy level of the vehicle may bedetermined. By categorizing the vehicle occupancy as one of multiplepossible occupancy levels, powertrain calibration may be accordinglyadjusted based on the occupancy level to enable a wide range of settingsthat vary in their bias between NVH and fuel economy. As a result, abetter balance between engine efficiency and occupant comfort can beprovided.

From each of 406, 410, 414, 418, and 420, the method moves to 422 todetermine if there is cargo present in the vehicle. For example, basedon sensors in the car truck, it may be determined if cargo is present.Alternatively, it may be determined based on sensor input if cargo ispresent on a car rooftop, or in a trailer being towed by the vehicle. Ifyes, then at 424, the method includes further adjusting powertraincalibration settings at the given occupancy level in view of thepresence of cargo.

Turning now to FIG. 5, an example method 500 for adjusting EGR operationduring autonomous vehicle operation with reduced occupancy level isshown. Method 500 may be performed in coordination with method 300 atFIG. 3. Method 500 will be described herein with reference to thecomponents and systems depicted in FIGS. 1A, 1B, and 2, though it shouldbe understood that the method may be applied to other systems withoutdeparting from the scope of this disclosure. Instructions for carryingout method 500 may be executed by a controller, such as controller 12 atFIGS. 1A, 1B, and 2, based on instructions stored in non-transitorymemory of the controller, and in conjunction with signals received fromsensors of the vehicle system, such as the sensors described above withreference to FIGS. 1A, 1B, and 2. The controller may employ actuators ofthe vehicle system, such as the actuators described with reference toFIGS. 1A, 1B, and 2, to adjust vehicle operation based on number ofoccupants. In particular, the controller may adjust exhaust gasrecirculation operation by adjusting position of an EGR valve, such asEGR valve 144 at FIG. 1B, via an actuator of the valve to increase fueleconomy while reducing NVH constraints when a lower occupancy level isdetected, according to the method 500 described below.

Method 500 begins at 502. At 502, method 500 includes determining ifengine is operating with exhaust gas recirculation enabled. For example,it may be determined that exhaust gas recirculation is enabled based ona position of the exhaust gas recirculation (EGR) valve. For example, anEGR valve position sensor may provide an indication of the EGR valveposition to the controller. If the EGR valve is closed, it may bedetermined that the EGR is not enabled, and method 500 proceeds to 510.If the EGR valve is not closed, it may be determined that the EGR isbeing supplied to the engine, and method 500 proceeds to 504.

At 504, method 500 includes increasing EGR supplied to the engine basedon reduced NVH constraints corresponding to the current occupancy levelof the vehicle. Increasing EGR may include, at 506, determining adesired EGR percentage of intake air based on engine speed, load, andreduced NVH constraints for the current occupancy level, the NVHconstraints reduced further from a nominal level as the occupancy leveldecreases (from the fifth highest towards the first lowest occupancylevel). Specifically, the desired EGR percentage of intake air may behigher when NVH constraints are lower than when NVH constraints arehigher. Thus, the desired EGR dilution is highest for a given enginespeed and load when the occupancy level is at the first occupancy level,and the EGR dilution reduces progressively as the occupancy levelincreases, the EGR dilution being lowest for the given engine speed andload when the occupancy level is at the fifth level.

In one example, a look up table mapping engine speed and load conditionsto desired EGR percentage may be used to determine a base desired EGRpercentage, the look up table further including a factor with which tomultiple the desired EGR percentage that is indicative of a degree ofNVH constraint reduction to be applied based on the occupancy level. Forexample, the controller may determine the desired EGR percentage basedon a calculation using the look-up table with the input being enginespeed and load and occupancy level, and the output being the desired EGRpercentage taking into account the corresponding level of NVH constraintreduction.

Further, based on the desired EGR percentage and mass air flow (MAF), adesired EGR flow may be calculated. The EGR valve is then adjusted, at508, based on the desired EGR flow to provide the desired EGR percentageof intake air. The EGR valve may be adjusted by a valve actuator basedon commands from the controller. In one example, when EGR is provided asa fixed percentage of intake air within a speed-load range (e.g. low tomid speed load range), the fixed percentage of intake air may be higherwhen NVH constraints are reduced than when nominal NVH constraints areused. In one example, when variable EGR is provided based on enginespeed and load, the desired EGR percentage for a given speed and loadmay increase as NVH constraints are reduced relative to when nominal NVHconstraints are applied. After supplying the desired EGR, method 500 mayreturn.

Returning to 502, if it is confirmed that EGR is not on, method 500proceeds to 510. At 510, method 500 includes determining if EGR isdesired based on reduced NVH constraints. For example, during idleconditions, when nominal NVH constraints are used, the EGR may not bedelivered (that is desired EGR may be zero) in order to reduce idleroughness when engine is operating at idle speed and load. However, asthe occupancy level of the vehicle decreases, and the vehicle is drivenautonomously, NVH constraints may be reduced and EGR may be supplied toimprove fuel economy during idle conditions. The EGR percentage may notexceed a first threshold, where the first threshold is based on anamount of EGR that can cause engine stalling under idle conditions.Thus, the amount of EGR supplied during idle conditions may be greaterthan zero but less than the first threshold such that fuel economy andemission benefits may be realized without causing engine stalling orsevere combustion instability. In another example, when nominal NVHconstraints are used, during rough road conditions (that is, when thevehicle is traveling on rough road), EGR may be disabled to reduce NVHand improve drivability. However, as the occupancy level decreases, theNVH constraints may be relaxed. Accordingly, when the vehicle istravelling on rough road, EGR may not be disabled and a desired EGRpercentage may be increased as the occupancy level decreases forimproved fuel economy and emissions. The desired EGR percentage may bebased on engine speed and load, and reduced NVH constraints. In yetanother example, in vehicles equipped with an EGR cooler, when nominalNVH constraints are applied, during cold start conditions, EGR may bedisabled for a threshold duration after light-off until a desired EGRcooler temperature is reached. Delaying EGR after catalyst light-offprovides reduced NVH and increases drivability. However, as theoccupancy level decreases, the delay in providing EGR may be reduced. Asan example, when the occupancy level is the lowest, the desired EGR maybe provided without any delay after catalyst light-off temperature isreached in order to improve fuel economy.

At 510, if it is determined that EGR is desired, method 500 proceeds to512. At 512, method 500 includes delivering EGR, the EGR percentagedetermined based on reduced NVH constraints corresponding the determinedoccupancy level in addition to engine speed and load conditions.Accordingly, delivering EGR includes, at 514, determining a desired EGRpercentage based on engine speed and load, and the occupancy level.Based on the desired EGR percentage and mass air flow (MAF), a desiredEGR flow may be calculated. The EGR valve is then adjusted, at 516,based on the desired EGR flow to provide the desired EGR percentage ofintake air.

Returning to 510, if it is judged that EGR is not desired, method 500proceeds to 518. For example, during cold start conditions, forexpediting catalyst light-off, it may be desirable to stop EGR flowuntil a threshold temperature is reached. Under such conditions, whenthe exhaust catalyst temperature is below the light-off temperature, EGRmay not be provided and vehicle operation may be maintained without EGRuntil conditions for EGR delivery based on engine speed and load, andreduced NVH constraints are satisfied (e.g. until exhaust catalysttemperature measured based on an indication from an exhaust catalysttemperature sensor reaches a threshold light-off temperature).

In this way, for a given engine speed and load after an engine coldstart, the EGR flow may be increased from a nominal level as theoccupancy level of the vehicle decreases, while maintaining the EGR flowabove a threshold based on combustion stability limits (or misfirelimits) of the engine.

Turning to FIG. 6A, an example method 600 is shown for adjusting a VDEmode of engine operation based on an occupancy level of the vehicle.Specifically, an operating range of the VDE mode may be expanded as theoccupancy level decreases to improve fuel economy. Method 600 may beperformed in coordination with method 300 at FIG. 3. Method 600 will bedescribed herein with reference to the components and systems depictedin FIGS. 1A, 1B, and 2, though it should be understood that the methodmay be applied to other systems without departing from the scope of thisdisclosure. In particular, the controller may adjust VDE operation basedon reduced NVH constraints by adjusting one or more of an intake valve,an exhaust valve, spark timing, and fuel injection, to deactivate one ormore engine cylinders during VDE mode, via one or more of an intakevalve actuator, an exhaust valve actuator, a spark plug actuator, and afuel injector actuator, to increase fuel economy while compromising NVHas the occupancy level decreases, according to the method 600 describedbelow.

Method 600 begins at 602. At 602, method 600 includes judging if thevehicle is already operating in a VDE mode. For example, the vehicle maybe confirmed to be operating in the VDE mode if a number of cylindersare deactivated while a remaining number of cylinders are active.Deactivation of the cylinders may be determined based on the states ofone or more of intake valve, exhaust valve, fuel injectors, and sparkplug. If the answer at 602 is YES, the vehicle is operating in the VDEmode, and method 600 proceeds to 612. At 612, responsive to the vehiclebeing already in the VDE mode, the method includes transitioning to alower induction ratio than otherwise allowed, the lower induction ratioselected based on the occupancy level.

If the answer at 602 is NO, the vehicle is not operating in the VDEmode, and method 600 then proceeds to 604. At 604, method 600 includesdetermining if cylinder deactivation conditions are met based on reducedNVH constraints. For example, the vehicle and/or engine operatingconditions may be measured and/or estimated. Further, reduced NVHconstraints may be applied based on the occupancy level to determine ifit is possible to operate the vehicle in the VDE mode. For example, atnear-idle or idle speed conditions, when nominal NVH constraints areapplied, for smoother drive and better feel, VDE operation may bedisabled. This is because the associated NVH may be objectionable to avehicle occupant. However, operating the vehicle in the VDE mode duringidle or near-idle conditions may improve fuel economy. Therefore, as theoccupancy level of the vehicle decreases while the vehicle is operatingin an autonomous mode, NVH constraints may be reduced and engineoperation may be biased towards favoring fuel economy over NVH. In oneexample, based on the occupancy level, engine speed and load thresholdswithin which VDE operation may be performed may be adjusted.Specifically, as the occupancy level decreases, VDE operation may beenabled at lower engine speeds and loads in view of the reduced NVHconstraints as compared to the range where VDE operation is enabled withnominal NVH constraints. The controller may then determine, based on theadjusted threshold, if VDE operation is desired after applying reducedNVH constraints. If yes, at 608, the engine may switch to a VDE mode ofoperation earlier than otherwise allowed. In addition, at 610, theengine may operate at a lower induction ratio than otherwise allowed.

In a further example, a number of gears or gear ratios during which VDEoperation may be enabled can be varied when operating with reduced NVHconstraints. Typically, when nominal NVH constraints are employed,operation in VDE mode may be disabled during vehicle operation in afirst and/or second transmission gear. However, when NVH constraints arereduced due to lower occupancy levels, depending on torque requirements,VDE mode operation in the first and/or second gear may not be disabled.Thus, if torque requirements are satisfied, the engine may be allowed tooperate in the VDE mode when the current transmission ratio is in thefirst gear and/or the second gear in order to improve fuel economy.

Switching to VDE mode of operation, and operating the engine in the VDEmode includes, deactivating a number of cylinders by deactivating one ormore of intake valves, exhaust valves, spark, and fuel injection. Inthis way, a VDE operation boundary may be expanded to improve fueleconomy while compromising NVH when the occupancy level of the vehicleis lower, such as when there are no occupants, or when the occupant isnot an active driver.

Returning to 604, if cylinder deactivation conditions are not met, thenat 606, the method includes maintaining current vehicle operation.

While the present examples illustrate controlling VDE mode of operationindependent of other operations, it will be appreciated that duringconditions when reduced NVH constraints are employed, VDE operation maybe controlled in coordination with one or more other vehicle operations,such as torque converter operation, EGR operation etc.

FIG. 6B illustrates a graph showing operating range of VDE based ondifferent NVH constraints. The VDE operation is plotted against throttleopening and engine speed.

Rectangular boundary 652 indicates an example VDE operating range whennominal NVH constraints are applied. For example, when an active driveris present, or the vehicle is not operating in an autonomous mode,nominal NVH constraints may be applied, and VDE operation may berestricted to mid-range speeds, at low and/or moderate loads where aninduction ratio selection biases NVH over fuel economy.

Rectangular boundary 654 indicates an example operating range when NVHconstraints are not applied, such as may occur when the occupancy levelof the vehicle is lowest. This may occur, for example, when no occupantsare present. As the occupancy level goes from the highest level to thelowest level, such as may occur when the vehicle gets an occupant, orwhen an occupant moves from a passenger seat/role to a driver seat/role,the VDE operating range is changed from rectangular boundary 652 torectangular boundary 654. Thus, as the reduced NVH constraints areapplied at the decreasing occupancy level, VDE operation may be expandedto range more than nominal NVH constraints. In particular, VDE operationis extended to lower engine speeds and higher engine loads than when NVHis nominally constrained.

Turning now to FIG. 7A, a flow chart illustrating an example method 700for adjusting torque converter operation based on occupancy level tobias towards increased fuel economy while compromising drivability isshown. Method 700 may be performed in coordination with method 300 atFIG. 3. Method 700 will be described herein with reference to thecomponents and systems depicted in FIGS. 1A, 1B, and 2, though it shouldbe understood that the method may be applied to other systems withoutdeparting from the scope of this disclosure. In particular, thecontroller may adjust operation of a torque converter, such as torqueconverter 206 at FIG. 2, based on reduced NVH constraints via a torqueconverter actuator to increase fuel economy while compromising NVH asoccupancy level decreases, according to method 700 described below.

Method 700 begins at 702. At 702, method 700 includes determiningcurrent torque converter operation. For example, at 702, determiningcurrent torque converter operation includes determining a current sliprotation rate of the lock-up clutch. The current slip rotation rate maybe determined based on one or more of an impeller speed of the torqueconverter, a turbine speed of the torque converter, and a duty cycle ofa lock-up clutch solenoid.

Upon determining the current slip rotation rate, method 700 proceeds to704. At 704, method 700 includes determining a desired torque converteroperation. For example, at 704, determining the desired torque converteroperation includes shifting to a map for controlling torque converteroperation that corresponds to the occupancy level of the vehicle. Themap may include a torque converter schedule for an operational range ofspeed and load that favors fuel economy over NVH (that is, drivability),the operational range specific for the corresponding occupancy level.Thus, for a given engine speed and load, the desired torque converterslip rotation rate may decrease as the occupancy level decreases, thedecreased slip rotation rate favoring fuel economy over NVH as theoccupancy level decreases. The map may be stored in the memory of thecontroller, and may be utilized for determining the desired sliprotation rate in response to the controller determining the occupancylevel of the vehicle. An example torque converter slip schedule or mapis shown in FIG. 7B. Specifically, FIG. 7B illustrates directionality ofshift in the torque converter slip map when zero occupants are presentin the vehicle. Thus, the map that corresponds to zero occupants in thevehicle may be shifted as indicated in FIG. 7B.

In the example map illustrated in FIG. 7B, torque converter slip ismapped against throttle opening and engine speed. Line 710 represents100% desired slip for the torque converter while line 720 represents 0%desired slip for the torque converter. The desired slip is 0% whenengine operation falls on line 720 and torque converter is in a lockedstate. The desired slip is 100% when engine operation falls on line 710and the torque converter is in an unlocked state. However, between lines710 and 720, torque converter may be in a partially locked state. Forexample, lines 712, 714, 716, and 718 may represent 80%, 60%, 40% and20% slip respectively. In the partially locked state, the torqueconverter may be commanded to achieve the desired slip based on enginespeed and load conditions. Thus, when moving from line 710 to line 720,the degree of slip increases.

The torque converter map may be adjusted based on an occupancy level ofthe vehicle. For example, when there are multiple occupants in thevehicle, or when the vehicle is not being operated in an autonomousmode, the torque converter map may be adjusted towards line 710 suchthat nominal NVH constraints are applied, and NVH and drivability isfavored over fuel economy. During this time, the vehicle is adjustedtowards more slip. In comparison, when there are fewer occupants in thevehicle while the vehicle is being operated in an autonomous mode, suchas when there are no occupants, or when the occupant is a passenger or apassive driver, the torque converter map may be adjusted towards line720 such that reduced NVH constraints are applied, and fuel economy isfavored over NVH and drivability. During this time, the vehicle isadjusted towards less slip. The decrease in slip may favor fuel economyby decreasing torque loss during torque conversion. However, decrease inslip decreases fluidic coupling, which lessens the dampening effect oftorque fluctuations. As a result, drivability may be decreased. However,when vehicle occupancy level is lower, concern for drivability may becompromised for fuel economy improvement.

The shifting of the torque converter map based on occupancy level may beperformed based on NVH tolerance limits. Specifically, the NVH tolerancelimits may be increased when the occupancy level is lower. Therefore, adegree of shift towards less slip may be based on increase in the NVHtolerance limits. In this way, for a given engine speed and load, thedesired slip rotation rate may be lower when the occupancy level islower than a slip rotation rate when the occupancy level is higher.

Returning to FIG. 7A, upon determining the desired slip rotation rate at704, method 700 proceeds to 706. At 706, method 700 includes adjustingone or more actuators to modify current torque converter operation basedon the desired torque converter operation. For example, responsive to alower desired degree of slip at a lower occupancy level, the controllermay send signals to a lock-up clutch actuator to decrease the slip ofthe lock-up clutch such that a target engagement state (and hencedesired slip) of the lock-up clutch is achieved. The routine then ends.

In some examples, method 700 may be performed in response to anoccupant-selected mode wherein the occupant chooses to operate thevehicle for increased fuel economy while compromising drivability. Thus,the lock-up clutch operation may be modified based on anoccupant-selected setting. Specifically, the controller may modify thelock-up clutch operation based on the occupant selected setting receivedfrom a vehicle interface. For example, when an occupant selects asetting that favors improved fuel economy over NVH, the controller maydecrease the desired slip of the torque converter. The desired slip maybe determined based on a map that is adjusted towards less slip whenoccupant favors fuel economy. On the other hand, when the occupantselects a setting that favors improved NVH, the controller may increasethe desired slip of the torque converter. In this case, the desired slipmay be determined based on a map that is adjusted towards more slip whenoccupant favors drivability.

Turning to FIG. 8A, an example method 800 for adjusting lugging limitsof the engine based on occupancy level is shown. Lugging may be referredto a condition that occurs when the vehicle is operating in high gearwith a lower engine speed (e.g., below 2000 rpm). When vehicleacceleration is desired under these conditions, the engine may generateless torque and hence, may struggle to give the desired motion to thevehicle. Thus, the acceleration is low. Due to high load and low enginespeeds, firing frequency is low which causes driveline disturbances.Such driveline vibrations may be experienced by the vehicle occupants asone or more of seat track vibration, steering wheel vibration, andinterior cabin boom sound. Typically, NVH due to lugging may becontrolled through the torque converter, which transmits and amplifiestorque from the engine to the transmission using fluid coupling. Forexample, torque converter slip may be increased during luggingconditions in order to dampen the effect of vibrations produced duringlugging. In this way, drivability is improved. However, increasingtorque converter slip decreases fuel economy due to fluid coupling andclutch friction. Therefore, as the occupancy level decreases, NVH due tolugging may be better tolerated in order to increase fuel economy.Method 800 may be performed in coordination with method 300 at FIG. 3.Method 800 will be described herein with reference to the components andsystems depicted in FIGS. 1A, 1B, and 2, though it should be understoodthat the method may be applied to other systems without departing fromthe scope of this disclosure. The controller may employ actuators of thevehicle system, such as the actuators described with reference to FIGS.1A, 1B, and 2, to adjust vehicle operation based on number of occupants.In particular, the controller may adjust torque converter operationbased on reduced NVH constraints via a torque converter actuator toincrease fuel economy while compromising NVH based on occupancy level,according to the method 800 described below.

Method 800 begins at 802. At 802, method 800 includes adjusting lugginglimits, specifically, lugging NVH tolerance limits, based on reduced NVHconstraints. Adjusting lugging limits includes, at 804, increasing anNVH tolerance threshold as the occupancy level decreases. Adjustinglugging limits further includes, at 806, decreasing torque converterslip during lugging conditions as the occupancy level decreases. Anexample map illustrating torsional vibration at a given transmissionoutput over engine rpm at various slip rpm is shown at map 850 in FIG.8B. Line 810 indicates lugging limit corresponding to nominal NVHconstraints, and line 820 indicates an adjusted lugging limitcorresponding to reduced NVH constraints. Typically, when the occupancylevel is higher such as when the vehicle includes an active driver ormultiple passengers, or when the vehicle is not operated in theautonomous mode, the lugging limit may be set as indicated by line 810.During such conditions, at lower engine speeds, torque converter slip of30 rpm or lower would fail to meet the desired NVH target. Thus, vehiclemay not be operated with a torque converter slip of 30 or less in orderto meet desired NVH level and maintain drivability. In other words,torque converter operation is adjusted such that desired NVH levels aremaintained during lugging. However, a higher torque converter slip thatfavors drivability may decrease fuel economy. Therefore, when theoccupancy level in the vehicle is lower, such as when the vehicle isbeing operated autonomously with no occupants, with only a passenger ora passive driver, the lugging NVH tolerance limit may be increased(towards line 820) in order to allow the torque converter operation atlower slip, which improves fuel economy while compromising NVH. Map 850may be stored in the memory of the controller and may be used to selecta torque converter map corresponding to increased NVH tolerance limits,which may be used to determine the desired slip during engineconditions, such as lugging depending on the occupancy level of thevehicle.

In this way, NVH tolerance limits may be increased as occupancy leveldecreases so that during lugging conditions torque converter slip may bedecreased to increase fuel economy while compromising drivability.

Next, FIG. 9 shows a flow chart illustrating an example method 900 foradjusting transmission shifting based on reduced NVH constraints.Specifically, method 900 may be performed as the occupancy level in thevehicle decreases. Method 900 may be performed in coordination withmethod 300 at FIG. 3. The controller may employ actuators of the vehiclesystem, such as the actuators described with reference to FIGS. 1A, 1B,and 2, to adjust vehicle operation based on number of occupants.

Method 900 begins at 902. At 902, method 900 includes utilizing atransmission shift schedule based on progressively reduced NVHconstraints as the occupancy level decreases. Specifically, upshift anddownshift decisions may be based on reduced NVH constraints. Thetransmission shift schedule based on reduced NVH constraints may favorfuel economy. This includes, at 910, lock the torque converter moreaggressively as the occupancy level decreases. For example, a degree ofslip of the torque converter may be reduced as the occupancy leveldecreases. At 912, the method includes maintaining the torque converterlocked during transmission gear shifts when the occupancy level ishigher, such as higher than a threshold.

At 914, the method includes upshifting early at lower engine rpm. Forexample, the transmission may launch in higher gears than typicallyallowed when operating with nominal NVH constraints. At 916, the methodincludes reducing the number of downshifts. Further still, thecontroller may instantaneously select the optimal gear for fuelefficiency that meets the vehicle acceleration demand withoutconsidering shift quality or shifts that are traditionally difficult toexecute smoothly. This allows the transmission to execute shifts withoutcompensating for the torque hole. In this way, transmission shifting maybe adjusted for improved fuel economy while compromising NVH based onoccupancy level.

Turning next to FIG. 10, a flow chart illustrating an example method1000 for adjusting DFSO operation based on reduced NVH constraints isshown. Method 1000 may be performed in response to an occupancy level ofthe vehicle when the vehicle is operating in an autonomous mode. Method1000 may be performed in coordination with method 300 at FIG. 3. Thecontroller may employ actuators of the vehicle system, such as theactuators described with reference to FIGS. 1A, 1B, and 2, to adjustvehicle operation. In particular, the controller may adjust DFSOoperation based on reduced NVH constraints by adjusting operation of afuel injector, such as fuel injector 69 at FIG. 2, via a fuel injectoractuator, to increase fuel economy while compromising NVH, according tothe method 1000 described below.

Method 1000 begins at 1002. At 1002, method 1000 includes judging if theengine is operating under deceleration fuel shut off (DFSO) conditions.DFSO condition is a non-fueling condition during which fuel supply isinterrupted but the engine continues spinning and at least one intakevalve and one exhaust valve are operating; thus, air is flowing throughone or more of the cylinders, but fuel is not injected in the cylinders.Under DFSO conditions, fuel injector is deactivated, and combustion isnot carried out and ambient air may move through the cylinder from theintake passage to the exhaust passage. Accordingly, DFSO conditions maybe confirmed based on fuel injector deactivation in one or more, or allengine cylinders in addition to one or more of vehicle speed, throttleposition, engine speed, and engine load. If DFSO conditions areconfirmed, the answer at 1002 is YES, and method 1000 proceeds to 1004to maintain DFSO operation. The method then moves to 1016 to enable DFSOto be maintained over a longer duration of vehicle operation.

If the engine is not currently operating with DFSO, method 1000 proceedsto 1006 to more aggressively enter and re-enter DFSO conditions. Thisincludes relaxing DFSO entry conditions and extending the engine speed,load, and vehicle speed range at which DFSO can be entered. For example,the controller may extend DFSO entry conditions to lower gears andvehicle speeds.

At 1008, it may be determined if the relaxed DFSO entry conditions havebeen met. DFSO may be initiated responsive to one or more of vehiclespeed, vehicle acceleration, engine speed, engine load, throttleposition, and transmission gear position, and may occur repeatedlyduring a drive cycle. In one example, DFSO may be initiated if enginespeed is below a threshold speed, the threshold speed lowered relativeto nominal settings when the DFSO entry conditions are relaxed forreduced NVH constraints. In another example, DFSO may be initiated ifengine load is below a threshold, the threshold load lowered relative tonominal settings when the DFSO entry conditions are relaxed for reducedNVH constraints. In still another example, when operating in anautonomous mode, DFSO may be initiated based on an a throttle positionand/or a change in the throttle position for a suitable duration—e.g.,DFSO may be initiated if a threshold change in the throttle positionindicating deceleration request has occurred, DFSO entered responsive toa smaller threshold change in throttle position relative to nominalsettings when the DFSO entry conditions are relaxed for reduced NVHconstraints. Additionally or alternatively, DFSO may be initiated if thevehicle has remained in deceleration conditions (e.g., throttleremaining in a threshold open position) for a threshold duration, thethreshold duration reduced relative to nominal settings when the DFSOentry conditions are relaxed for reduced NVH constraints. Further,additionally or alternatively, entry into DFSO may be determined basedon a commanded signal to cease fuel injection.

If DFSO entry conditions are not met, the answer at 1004 is NO, andmethod 1000 proceeds to 1020. At 1020, method 1000 includes maintainingcurrent vehicle operation. If DFSO entry conditions are met, the answerat 1008 is YES, and method 1000 proceeds to 1012.

At 1012, method 1000 includes transitioning to DFSO operationimmediately. For example, poor drivability may become an issue duringdeceleration fuel shut off (DFSO). Specifically, poor drivability mayresult due to transmission or driveline gear lash. For example, when theengine transitions from exerting a positive torque to exerting anegative torque (or being driven), the gears in the transmission ordriveline separate at the zero torque transition point. Then, afterpassing through the zero torque point, the gears again make contact totransfer torque. This series of events produces an impact, or clunk.Further, the effects of transmission gear lash can be amplifieddepending on the state of the transmission. For example, sensitivity tonoise, vibration, and harness (NVH) may be higher in all wheel drive or4×4 operation, compared with two-wheel drive operation. Further, suchsensitivity may also be increased as the overall transmission gear islower, such as to a 4×4 low gear. When NVH is constrained, in order toimprove drivability, deactivation of the fuel injection duringdeceleration operation is restricted when the vehicle is in an All WheelDrive, or 4×4, low gear. Further, clunk may be more perceptible orperceptible at certain vehicle speeds less than a clunk threshold.During such conditions as well, DFSO may be disabled. Further,deactivation of fuel injectors may be delayed until engine speedstabilizes in order to reduce NVH. However, limiting DFSO or delayingDFSO impacts fuel economy. Therefore, when NVH constraints are reduceddue to reduced occupancy level, while the vehicle is operatingautonomously, NVH may be tolerated largely and concern for drivabilityis reduced.

Thus, when the occupancy level of the vehicle is lower, and the vehicleis operating in an autonomous mode, DFSO operation may be expanded to awider range of operating conditions, and fuel injection deactivation maybe performed immediately upon DFSO entry conditions being met.Specifically, DFSO may be performed during all wheel and/or low gearoperation. Further, the clunk threshold may be decreased so that DFSO isperformed at lower vehicle speeds. Further still, DFSO may be initiatedimmediately in response to entry conditions being met, without delayingDFSO until engine speed stabilizes. This includes, at 1014, deactivatingfuel injection in all cylinders.

At 1016, the method further includes extending DFSO exit conditions tohigher gears and vehicle speeds. At 1018, it may be determined if therelaxed exit conditions have been met. If not, DFSO operation ismaintained at 1020. Else, if exit conditions have been met, then at1022, the cylinder fuel injectors of the deactivated cylinders arereactivated, and combustion is resumed in those cylinders.

For example, it may be determined if the brake has been released or ifan amount of brake release is greater than a threshold, where thethreshold is based on reduced NVH constraints. When the vehicle isoccupancy is lower and the vehicle is operating autonomously,application of brakes may be determined based on brake pressure, forexample.

When vehicle occupancy is higher, or when the vehicle is not operatingautonomously, in order to mitigate clunk and improve tip-in response,exit from DFSO may be performed early. Specifically, since it takes acertain duration (e.g., amount of time, or number of engine cycles) tore-enable engine firing, a driver may easily feel clunk on exit of DFSOif the injectors, combustion, transmission control and engine torquecontrol do not have adequate time to stabilize. Thus, a driver's tip-inmay be anticipated so as to prepare torque control prior to the tip-inevent by making use of the brake input and effort. In this way, theengine is given sufficient time to prepare the reactivation of fuelinjection. Thus, the engine may provide required torque once the drivertips-in and powertrain NVH may be reduced. However, when the vehicleoccupancy is lower, NVH constraints are reduced and fuel economy isprioritized. Therein, an exit from DFSO may be delayed. Accordingly, thethreshold amount brake release may be increased (that is, thresholdamount of break release for DFSO exit when vehicle occupancy is highermay be less than the threshold amount of brake release for DFSO exitwhen vehicle occupancy is lower) so that DFSO can be performed moreaggressively for an extended amount of time with reduced NVHconstraints. In this way, greater fuel economy may be achieved with thevehicle operating in an autonomous mode. Overall, DFSO may be enteredand re-entered more aggressively at a wider range of operatingconditions, and without delay based on vehicle occupancy so that fueleconomy is prioritized over drivability.

Turning now to FIG. 11, a flow chart illustrating an example method 1100for adjusting the execution schedule of one or more on-board diagnosticroutines based on reduced NVH constraints is shown. Method 1100 may beperformed in response to an occupancy level of the vehicle when thevehicle is operating in an autonomous mode. Method 1100 may be performedin coordination with method 300 at FIG. 3. The controller may employactuators of the vehicle system, such as the actuators described withreference to FIGS. 1A, 1B, and 2, to adjust vehicle operation. Inparticular, the controller may the initiation and/or completion of oneor more diagnostic routines and monitors based on reduced NVHconstraints to increase fuel economy, according to the method 1100described below.

Method 1100 begins at 1102. At 1102, method 1100 includes adjusting thethreshold for intrusive and/or adaptive diagnostics to account for lowerNVH constraints. These include adjusting the entry and/or executionconditions for monitors related to adaptive knock, clutch slip, DPFregeneration, etc. The entry conditions include one or more of enginespeed, load, vehicle speed, etc., conditions that need to be satisfiedfor a monitor to be initiated. The execution conditions include one ormore of engine speed, load, vehicle speed, etc., conditions that need tobe satisfied for the monitor to continue to run. Typically, the entryand execution conditions may be adjusted to reduce drivability issues.For example, when a knock monitor is run, low grade vibrations and knockmay be intentionally induced to determine if the engine's spark controlis able to address the knock sufficiently, and in a timely manner.However, the knock related vibrations may be objectionable to a vehicledriver. So the knock monitor execution may be delayed until conditionswhere the knock is less objectionable, such as when operating thevehicle at high speeds where the ambient noise may mask the knock noise.This can result in the engine operating with insufficient adaptive knockcontrol for a duration until the monitor is run. Therefore, by relaxing(specifically, lowering) the vehicle speed threshold at which the knockmonitor can be executed, knock monitor completion is better ensured,which improves adaptive spark application. Due to the lower occupancylevel of the vehicle when the NVH constraints are reduced, driveabilityis not a concern during the execution of the monitor.

At 1104, it may be determined if the relaxed entry conditions for agiven monitor have been met. For example, a particular monitor may beinitiated responsive to one or more of vehicle speed, vehicleacceleration, engine speed, engine load, throttle position, andtransmission gear position, and may occur repeatedly during a drivecycle. In one example, a monitor may be initiated if engine speed isbelow a threshold speed, the threshold speed lowered relative to nominalsettings when the entry conditions are relaxed for reduced NVHconstraints. In another example, a monitor may be initiated if engineload is below a threshold, the threshold load lowered relative tonominal settings when the entry conditions are relaxed for reduced NVHconstraints. At 1106, responsive to the relaxed entry conditions beingmet, the monitor is initiated and/or executed.

In this way, greater fuel economy may be achieved with the vehicleoperating in an autonomous mode by enabling diagnostics to be completedover a drive cycle. By relaxing monitor entry and execution conditionsso that the monitor can be entered and executed more aggressively over awider range of operating conditions of a drive cycle based on vehicleoccupancy, fuel economy is prioritized over drivability.

Turning now to FIG. 12, a flow chart illustrating an example method 1200for adjusting hybrid vehicle operation based on reduced NVH constraintsis shown. Method 1200 may be performed in response to an occupancy levelof the vehicle when the vehicle is operating in an autonomous mode.Method 1200 may be performed in coordination with method 300 at FIG. 3.The controller may employ actuators of the vehicle system, such as theactuators described with reference to FIGS. 1A, 1B, and 2, to adjustvehicle operation. In particular, the controller may adjust transitionsbetween an engine mode and an electric mode of vehicle propulsion, byadjusting the actuation of engine fuel injectors and the output of anelectric motor, such as motor 120 of FIG. 1, based on reduced NVHconstraints to increase fuel economy, according to the method 1200described below.

Method 1200 begins at 1202. At 1202, method 1200 includes determining ifthe vehicle is operating in an engine-on mode. This includes determiningif the engine is combusting fuel and if at least some engine torque isbeing used to propel the vehicle. In one example, the vehicle is in anengine-on mode when the vehicle is in an engine-only operation (whereinonly engine torque is used to propel the vehicle) or in hybrid assistoperation (wherein each of engine torque and motor torque is used topropel the vehicle).

If yes, then at 1206, the method includes propelling the vehicle usingat least some engine torque. At 1208, responsive to reduced NVHconstraints, the method includes reducing spark retard usage fordriveline lash crossing. Typically, when a driveline lash region iscrossed, a nominal amount of spark retard is used to reduce the NVHassociated with the driveline lash so as to improve vehicle drivability.However, the spark retard usage results in fuel economy beingcompromised. Therefore, when the vehicle is in an autonomous mode, sparkretard usage is reduced relative to the nominal amount as the occupancylevel decreases. Further still, at the lowest level of occupancy, nospark retard may be applied. Consequently, the vehicle controller maynot mitigate driveline shuffle via inefficient spark retard usage. Thecontroller may select the amount of spark retard to apply via a look-uptable that uses transmission gear, engine speed, and engine load asinputs, to generate the spark amount as an output.

At 1210, while operating in the engine-on mode, it may be determined ifa regenerative braking opportunity is available, such as during adeceleration event. In one example, during a deceleration event, such aswhen an operator releases an accelerator pedal or applies a brake pedal,vehicle speed may be reduced by recuperating the wheel torque and usingit to operate the electric motor of the HEV as a generator. As a result,wheel torque is recuperated and saved as electric energy in a systembattery. By decelerating the vehicle via recuperating the wheel torque,the need for brake application is reduced, improving vehicle fueleconomy.

If a regenerative braking energy opportunity is available whileoperating in the autonomous mode, then at 1212, the method includesdisconnecting the engine from the driveline, such as by slipping thetorque converter clutch to unlock it. The controller may then charge theHEV battery by recovering wheel torque. During the battery charging, theengine may remain decoupled from the driveline. This may includemaintaining the engine disconnected even into lower gears and lowervehicle speeds responsive to a reduced occupancy level of the vehicle.This allows the vehicle to recover more of the regenerative brakingenergy. As one example, as the occupancy level decreases, the engine mayremain disconnected into progressively lower gears and lower vehiclespeeds relative to a speed and gear setting used when nominal NVHconstraints are applied. As a result, at 1214, the HEV battery may becharged more aggressively as the occupancy level decreases while thevehicle is in the autonomous mode. This allows the vehicle to be betterprepared for more electric mode operation (EV operation) to support aforthcoming passenger transport mission.

Returning to 1202, if an engine-on mode is not confirmed, then at 1204,an electric mode may be confirmed. Upon confirming the electric mode, at1220, the method includes propelling the vehicle using motor torque froman electric motor of the system. At 1222, it may be determined if enginerestart conditions are met. In one example, the engine may be restartedresponsive to a drop in the battery's state of charge (SOC) below athreshold SOC. In another example, the engine may be restarted if thedriver torque demand is larger than can be met only via the electricmotor. If engine restart conditions are not met, then the method returnsto 1220 to continue using motor torque to propel the engine. Else, ifengine restart conditions are met, then at 1224, the method includesrestarting the engine via bump start without using energy from startermotor, BISG, or HEV battery.

It will be appreciated that for each of the various powertraincalibration settings and schedules selected, such as those discussed atFIGS. 5-12, the controller may refer to a look-up table that uses enginespeed, load, and the determined occupancy level as inputs in selectingthe corresponding NVH constraint and the associated calibration setting.In one example, the calibration setting corresponding to a highestoccupancy level while the vehicle is in an autonomous mode may be morerelaxed and biased towards fuel economy than a nominal calibrationsetting used when the vehicle is not operated in the autonomous mode.Then as the occupancy level decreases, the settings may be furtherrelaxed and further biased towards fuel economy (over drivability). Inanother example, the calibration setting corresponding to a highestoccupancy level while the vehicle is in an autonomous mode may the sameas the nominal calibration setting used when the vehicle is not operatedin the autonomous mode.

It will be further appreciated that as the vehicle operating mode andoccupancy level changes over a drive cycle, the calibration settings maybe dynamically adjusted. A prophetic example of dynamically changingvehicle powertrain calibration settings over a drive cycle as thevehicle's occupancy level changes, and further as the vehicle shifts inand out of autonomous operation, is shown at FIG. 13. Specifically, map1300 depicts vehicle speed at plot 1302, the vehicle speed beingindicative of operator torque demand. Plot 1304 depicts whether anautonomous mode of vehicle operation (AV mode) is actuated on or off. Anoccupancy level of the vehicle when in the AV mode, as determined viasensor input, is shown at plot 1306. A transmission gear ratio is shownat plot 1308. An engine induction ratio (IR) that may be selected duringa variable displacement mode is shown at plot 1310. When all cylindersare active, the IR is 1.0. As cylinders are selectively deactivated, theIR drops. For example, when every alternate cylinder is deactivated, theIR is reduced to 0.5. An EGR flow rate is shown at plot 1312. When theEGR flow rate is higher, the engine dilution level is higher. EGR flowrate changes are enabled via adjustments to the opening of an EGR valverecirculating exhaust gas from an exhaust passage, downstream of anexhaust catalyst, to an intake passage, upstream of an intake throttle.All plots are shown over time along the x-axis.

Prior to t1, the vehicle is not operating in the AV mode. Therefore attime, the occupancy level is moot as all engine calibration settings areset to nominal NVH constraints wherein NVH is biased over fuel economy.However, the vehicle may be operating with a driver seated in a front ofthe vehicle, and multiple passengers seated in a rear of the vehicle. Atthis time, due to the elevated load, all engine cylinders are firing, asindicated by an IR of 1.0. The transmission is set to a third gear. EGRis being provided at a nominal level.

As the torque demand changes between t0 and t1, the transmission isdownshifted to a lower gear (herein from the third gear to a secondgear) and one of more cylinders are deactivated to operate the engine ata lower induction ratio. For example, the IR may be shifted from 1.0 to0.67 by deactivating one of four engine cylinders.

At t1, the primary occupant of the vehicle, that is the driver, changesthe vehicle operating mode to an autonomous vehicle (AV) mode, such asby selecting a button on a vehicle interface, which may be a dashboardor a display. For example, the driver may drive the vehicle to a highwaybetween t0 and t1, and at t1, upon reaching the highway, the driver mayselect the AV mode button. However, none of the occupants get out of thevehicle and so the occupancy level remains elevated, such as at a fourthlevel of occupancy due to the vehicle driver being present but notinteracting with vehicle steering and pedal controls.

Between t1 and t8, while still in the AV mode, the occupancy level ofthe vehicle changes. For example, the occupancy level may increase dueto a driver being active with the steering and pedal controls, or due toan occupant entering the vehicle. As another example, the occupancylevel may decrease due to one or all of the vehicle occupants exitingthe vehicle, due to a driver moving to a passenger seat, or due to adriver taking on a more passive role where they are not interacting withsteering and pedal controls. As the occupancy level changes, responsiveto the changing torque demand, the engine dilution provided via EGR, aninduction ratio, and a transmission gear shift schedule is varied.

For example, at t2, while in the AV mode, the vehicle driver starts totemporarily interact with steering controls, such as by operating thesteering wheel while the vehicle controller continues to manage thepedal controls. Responsive to the operator interaction, the determinedoccupancy level is raised. Due to the elevated occupancy level, as thetorque demand changes, transmission shifts are enabled with a schedulethat is biased more towards NVH than towards fuel economy. However, thetransmission shift schedule at the elevated occupancy level is stillmore biased towards fuel economy than a nominal schedule that is NVHconstrained (shown for reference by dashed line 1309), as would havebeen applied if the vehicle were not in the AV mode. For example, thetransmission shift schedule includes fewer downshifts and earlierupshifts as compared to the nominal schedule 1309.

As another example, the VDE transitions enabled while in the AV modewith varying occupancy level is more biased towards fuel economy than anominal schedule that is NVH constrained (shown for reference by dashedline 1311), as would have been applied if the vehicle were not in the AVmode. For example, the VDE mode transitions include earlier transitionsto lower induction ratios, and longer periods of engine operation withcylinder deactivation.

As another example, the EGR flow enabled while in the AV mode withvarying occupancy level is more biased towards fuel economy than anominal schedule that is NVH constrained (shown for reference by dashedline 1313), as would have been applied if the vehicle were not in the AVmode. For example, more EGR flow is provided at higher engine loads,enabling the engine dilution benefits to be provided over longer periodsof engine operation.

At t8, the vehicle driver disables the autonomous mode of vehicledriving. Accordingly, powertrain calibrations are returned to nominalsettings where the calibration is optimized for improved drivability andNVH at the cost of fuel economy.

In this way, vehicle calibration may be optimized as a function ofvehicle occupancy level when in an autonomous mode of operation. Bydynamically adjusting the settings as occupancy level changes over adrive cycle, engine component settings can be biased further towardsfuel economy while reducing NVH constraints. This allow additional fueleconomy benefits to be achieved while in an autonomous mode of vehicleoperation. By judging the occupancy level based on a number and locationof occupants in the vehicle, as well as based on an interaction level ofa primary occupant with vehicle controls, an appropriate bias betweenfuel economy and NVH can be determined while allows fuel economy to beimproved without degrading the drive quality perceived by an occupant.

One example method for operating a vehicle, comprises during anautonomous mode of vehicle operation, estimating an occupancy level ofthe vehicle based on a number of occupants, a position of each occupantwithin the vehicle, and a drive activity level of a primary occupant;and altering noise, vibration, and harshness (NVH) limits for apowertrain of the vehicle responsive to the occupancy level. In thepreceding example, additionally or optionally, estimating the occupancylevel of the vehicle based on a position of each occupant within thevehicle includes estimating based on whether an occupant is seated in adriver seat or a passenger seat, and further if the passenger seat is ina front or a rear of the vehicle. In any or all of the precedingexamples, additionally or optionally, estimating the occupancy level ofthe vehicle based on the drive activity level of the primary occupantincludes estimating whether the primary occupant is actuating one ormore of a steering wheel, an accelerator pedal, and a brake pedal of thevehicle. In any or all of the preceding examples, additionally oroptionally, the estimating is based on sensor input received from one ormore sensors including a seat occupancy sensor, a pressure sensor, acapacitative touch sensor, an infra-red sensor. In any or all of thepreceding examples, additionally or optionally, the estimating isfurther based on input from one or more of a camera, a microphone,communication received from a cloud dispatch, and communication receivedfrom another vehicle via V2X communication. In any or all of thepreceding examples, additionally or optionally, altering the NVH limitsresponsive to the occupancy level includes increasing an NVH thresholdrelative to a nominal NVH threshold as the occupancy level decreases,the nominal NVH threshold applied when the vehicle is not in theautonomous mode of operation, and adjusting one or more parameters ofpowertrain operation based on the increasing NVH threshold. In any orall of the preceding examples, additionally or optionally, thepowertrain includes an engine coupled to a transmission through a torqueconverter and wherein adjusting one or more parameters of the powertrainbased on the increasing NVH threshold includes adjusting one or more ofan idle operation of the engine, a variable displacement engine (VDE)mode of engine operation, a torque converter slip, shut off fuelsupplied to the engine during deceleration (DFSO) operation, atransmission shift schedule, a variable cam timing setting, and anexhaust gas recirculation percentage of recirculated exhaust gas and airinducted into the engine for combustion. In any or all of the precedingexamples, additionally or optionally, adjusting one or more powertrainparameters based on the increasing NVH threshold further includes, at agiven engine speed and load, operating at a lower than nominal inductionratio as the occupancy level decreases and the NVH threshold increases,switching to the variable displacement engine (VDE) mode of engineoperation during an idle condition, and increasing an amount of sparkretard applied to engine combustion during the idle condition. In any orall of the preceding examples, additionally or optionally, adjusting oneor more powertrain parameters based on the increasing NVH thresholdfurther decreasing torque converter slip as the occupancy leveldecreases and NVH threshold increases. In any or all of the precedingexamples, additionally or optionally, the method further comprisesreducing an accessory load applied by an air conditioning unit of thevehicle as the occupancy level decreases. In any or all of the precedingexamples, additionally or optionally, adjusting one or more powertrainparameters based on the increasing NVH threshold further includes,responsive to a deceleration greater than a threshold, transitioningimmediately to a deceleration fuel shut off (DFSO) operation duringwhich fuel supplied to an engine of the powertrain for combustion isshut off, where the threshold is based on the increasing NVH limit, anddelaying exit from the deceleration fuel shut off (DFSO) operation to alower a vehicle speed threshold below which deactivated fuel injectorsare reactivated. In any or all of the preceding examples, additionallyor optionally, the powertrain further includes an electric motor andwherein adjusting one or more parameters of the powertrain based on theincreasing NVH threshold includes, during vehicle deceleration, reducingvehicle speed by recuperating wheel torque via the electric motor tocharge a system battery while disconnecting the engine from thepowertrain, the engine maintained disconnected into a lower transmissiongear and/or a lower vehicle speed as the occupancy level decreases. Inany or all of the preceding examples, additionally or optionally, themethod further comprises intrusively initiating one or more on-boarddiagnostic routines of the vehicle responsive to the increased NVHlimits, the diagnostic routines initiated at one or more of a lowervehicle speed, a lower engine speed, and a lower engine load as theoccupancy level decreases.

Another example method for a vehicle comprises: setting different noisevibration and harshness (NVH) limits for a vehicle powertrain based asensed occupancy level of the vehicle, the occupancy level sensed whilethe vehicle is in an autonomous mode of operation based on each of anumber of occupants in the vehicle, a position of each occupant withinthe vehicle, and a degree of interaction of a primary occupant withvehicle steering and pedal controls. In any or all of the precedingexamples, additionally or optionally, setting different NVH limitsincludes: responsive to detecting zero occupants, indicating a first,lowest occupancy level and setting a first NVH tolerance threshold,higher than a nominal threshold; responsive to detecting only passengeroccupants, indicating a second occupancy level, higher than the firstoccupancy level, and setting a second threshold, higher than the firstNVH tolerance threshold; responsive to detecting a passive driveroccupant, indicating a third occupancy level, higher than the secondoccupancy level, and setting a third threshold, higher than the secondNVH tolerance threshold; responsive to the driver occupant interactingwith only one of a vehicle steering and a braking control, indicating afourth occupancy level, higher than the third occupancy level, andsetting a fourth threshold, higher than the third NVH tolerancethreshold; responsive to the driver occupant interacting with each ofthe vehicle steering and braking control, indicating a fifth occupancylevel, higher than the fourth occupancy level, and setting a fifththreshold, higher than the fourth NVH tolerance threshold; and selectinga vehicle component calibration setting based on the NVH limit. In anyor all of the preceding examples, additionally or optionally, selectingthe vehicle component calibration setting based on the NVH limitincludes: as the NVH limit moves from the first threshold to the fifththreshold, reducing a vehicle speed at which a transmission upshift isenabled and cylinder fueling is disabled, and reducing an accessory loadapplied by an air conditioning system on an engine. In any or all of thepreceding examples, additionally or optionally, the selecting furtherincludes increasing one or more of a desired EGR amount, and anoperating range of DFSO operation as the NVH limit moves from the firstthreshold to the fifth threshold. In any or all of the precedingexamples, additionally or optionally, the powertrain includes an engineand an electric motor coupled to a transmission through a torqueconverter, and adjusting one or more operating parameters of the vehicleincludes one or more of decreasing a percentage of torque converter slipas the NVH limit moves from the first threshold to the fifth threshold.

Another example vehicle system, comprises a variable displacement engine(VDE) including a plurality of cylinders, where one or more of thecylinders are deactivated in a variable displacement mode of engineoperation, the engine being coupled to a transmission through a torqueconverter; an occupant sensing system for detecting presence of anoccupant within the vehicle, the occupant sensing system including oneor more seat pressure sensors coupled to each vehicle seat; one or moreautonomous driving sensors; an in-vehicle computing system including anautonomous driving module, the autonomous driving module includinginstructions for operating the vehicle in an autonomous mode based onsignals received from the one or more autonomous driving sensors; and aprocessor and a storage device, the storage device storing instructionsexecutable by the processor to: estimate an occupancy level of thevehicle based on a number, location, and activity level of occupantswithin the vehicle; during a first condition including when theoccupancy level is higher than a threshold, adjusting one or morevehicle operating parameters based on a lower noise, vibration, andharshness (NVH) threshold of the vehicle; and during a second conditionincluding when the occupancy level is lower than the threshold,adjusting the one or more vehicle operating parameters based on a higherNVH threshold of the vehicle for increasing fuel economy improvementwhile compromising NVH; wherein the one or more vehicle operatingparameters include a desired amount of exhaust gas recirculated into theengine (EGR), a first engine speed and load range for variabledisplacement operation, a number of cylinders deactivated during thevariable displacement mode, a second engine speed and load range forshut off of fuel supplied to the engine during deceleration (DFSO)operation, torque converter slip, an accessory load applied on theengine, and a transmission shift schedule. In any or all of thepreceding examples, additionally or optionally, adjusting one or morevehicle operating parameters based on the higher NVH threshold includesincreasing the desired EGR amount, reducing the first speed and loadrange for variable displacement operation, reducing the number ofcylinders deactivated during the variable displacement mode, reducingthe second engine speed and load range for DFSO operation, decreasingtorque converter slip, and decreasing the accessory load applied on theengine as the occupancy level decreases.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A method for operating a vehicle,comprising: during an autonomous mode of vehicle operation, estimatingan occupancy level of the vehicle based on a number of occupants, aposition of each occupant within the vehicle, and a drive activity levelof a primary occupant; and altering noise, vibration, and harshness(NVH) limits for a powertrain of the vehicle responsive to the occupancylevel, wherein altering the NVH limits responsive to the occupancy levelincludes increasing an NVH threshold relative to a nominal NVH thresholdas the occupancy level decreases, the nominal NVH threshold applied whenthe vehicle is not in the autonomous mode of operation, and adjustingone or more parameters of powertrain operation based on the increasingNVH threshold, wherein the powertrain includes an engine coupled to atransmission through a torque converter and wherein adjusting one ormore parameters of the powertrain based on the increasing NVH thresholdincludes adjusting one or more of an idle operation of the engine, avariable displacement engine (VDE) mode of engine operation, a torqueconverter slip, shut off fuel supplied to the engine during deceleration(DFSO) operation, a transmission shift schedule, a variable cam timingsetting, and an exhaust gas recirculation percentage of recirculatedexhaust gas and air inducted into the engine for combustion.
 2. Themethod of claim 1, wherein estimating the occupancy level of the vehiclebased on a position of each occupant within the vehicle includesestimating based on whether an occupant is seated in a driver seat or apassenger seat, and further if the passenger seat is in a front or arear of the vehicle.
 3. The method of claim 1, wherein estimating theoccupancy level of the vehicle based on the drive activity level of theprimary occupant includes estimating whether the primary occupant isactuating one or more of a steering wheel, an accelerator pedal, and abrake pedal of the vehicle.
 4. The method of claim 1, wherein theestimating is based on sensor input received from one or more sensorsincluding a seat occupancy sensor, a pressure sensor, a capacitativetouch sensor, an infra-red sensor.
 5. The method of claim 4, wherein theestimating is further based on input from one or more of a camera, amicrophone, communication received from a cloud dispatch, andcommunication received from another vehicle via V2X communication. 6.The method of claim 1, wherein adjusting one or more powertrainparameters based on the increasing NVH threshold further includes, at agiven engine speed and load, operating at a lower than nominal inductionratio as the occupancy level decreases and the NVH threshold increases,switching to the variable displacement engine (VDE) mode of engineoperation during an idle condition, and increasing an amount of sparkretard applied to engine combustion during the idle condition.
 7. Themethod of claim 1, wherein adjusting one or more powertrain parametersbased on the increasing NVH threshold further decreasing torqueconverter slip as the occupancy level decreases and NVH thresholdincreases.
 8. The method of claim 1, wherein adjusting one or morepowertrain parameters based on the increasing NVH threshold furtherincludes, responsive to a deceleration greater than a threshold,transitioning immediately to a deceleration fuel shut off (DFSO)operation during which fuel supplied to an engine of the powertrain forcombustion is shut off, where the threshold is based on the increasingNVH limit, and delaying exit from the deceleration fuel shut off (DFSO)operation to a lower a vehicle speed threshold below which deactivatedfuel injectors are reactivated.
 9. The method of claim 1, furthercomprising, reducing an accessory load applied by an air conditioningunit of the vehicle as the occupancy level decreases.
 10. The method ofclaim 1, wherein the powertrain further includes an electric motor andwherein adjusting one or more parameters of the powertrain based on theincreasing NVH threshold includes, during vehicle deceleration, reducingvehicle speed by recuperating wheel torque via the electric motor tocharge a system battery while disconnecting the engine from thepowertrain, the engine maintained disconnected into a lower transmissiongear and/or a lower vehicle speed as the occupancy level decreases. 11.The method of claim 10, wherein selecting the vehicle componentcalibration setting based on the NVH limit includes: as the NVH limitmoves from the first threshold to the fifth threshold, reducing avehicle speed at which a transmission upshift is enabled and cylinderfueling is disabled, and reducing an accessory load applied by an airconditioning system on an engine.
 12. The method of claim 11, whereinthe selecting further includes increasing one or more of a desired EGRamount, and an operating range of DFSO operation as the NVH limit movesfrom the first threshold to the fifth threshold.
 13. The method of claim11, wherein the powertrain includes an engine and an electric motorcoupled to a transmission through a torque converter, and adjusting oneor more operating parameters of the vehicle includes one or more ofdecreasing a percentage of torque converter slip as the NVH limit movesfrom the first threshold to the fifth threshold.
 14. The method of claim1, further comprising: intrusively initiating one or more on-boarddiagnostic routines of the vehicle responsive to the increased NVHlimits, the diagnostic routines initiated at one or more of a lowervehicle speed, a lower engine speed, and a lower engine load as theoccupancy level decreases.
 15. A method for a vehicle, comprising:setting different noise vibration and harshness (NVH) limits for avehicle powertrain based a sensed occupancy level of the vehicle, theoccupancy level sensed while the vehicle is in an autonomous mode ofoperation based on each of a number of occupants in the vehicle, aposition of each occupant within the vehicle, and a degree ofinteraction of a primary occupant with vehicle steering and pedalcontrols, wherein setting different NVH limits includes: responsive todetecting zero occupants, indicating a first, lowest occupancy level andsetting a first NVH tolerance threshold, higher than a nominalthreshold; responsive to detecting only passenger occupants, indicatinga second occupancy level, higher than the first occupancy level, andsetting a second threshold, higher than the first NVH tolerancethreshold; responsive to detecting a passive driver occupant, indicatinga third occupancy level, higher than the second occupancy level, andsetting a third threshold, higher than the second NVH tolerancethreshold; responsive to the driver occupant interacting with only oneof a vehicle steering and a braking control, indicating a fourthoccupancy level, higher than the third occupancy level, and setting afourth threshold, higher than the third NVH tolerance threshold;responsive to the driver occupant interacting with each of the vehiclesteering and braking control, indicating a fifth occupancy level, higherthan the fourth occupancy level, and setting a fifth threshold, higherthan the fourth NVH tolerance threshold; and selecting a vehiclecomponent calibration setting based on the NVH limit.
 16. A vehiclesystem, comprising: a variable displacement engine (VDE) including aplurality of cylinders, where one or more of the cylinders aredeactivated in a variable displacement mode of engine operation, theengine being coupled to a transmission through a torque converter; anoccupant sensing system for detecting presence of an occupant within thevehicle, the occupant sensing system including one or more seat pressuresensors coupled to each vehicle seat; one or more autonomous drivingsensors; an in-vehicle computing system including an autonomous drivingmodule, the autonomous driving module including instructions foroperating the vehicle in an autonomous mode based on signals receivedfrom the one or more autonomous driving sensors; and a processor and astorage device, the storage device storing instructions executable bythe processor to: estimate an occupancy level of the vehicle based on anumber, location, and activity level of occupants within the vehicle;during a first condition including when the occupancy level is higherthan a threshold, adjusting one or more vehicle operating parametersbased on a lower noise, vibration, and harshness (NVH) threshold of thevehicle; and during a second condition including when the occupancylevel is lower than the threshold, adjusting the one or more vehicleoperating parameters based on a higher NVH threshold of the vehicle forincreasing fuel economy improvement while compromising NVH; wherein theone or more vehicle operating parameters include a desired amount ofexhaust gas recirculated into the engine (EGR), a first engine speed andload range for variable displacement operation, a number of cylindersdeactivated during the variable displacement mode, a second engine speedand load range for shut off of fuel supplied to the engine duringdeceleration (DFSO) operation, torque converter slip, an accessory loadapplied on the engine, and a transmission shift schedule.
 17. The systemof claim 16, wherein adjusting one or more vehicle operating parametersbased on the higher NVH threshold includes increasing the desired EGRamount, reducing the first speed and load range for variabledisplacement operation, reducing the number of cylinders deactivatedduring the variable displacement mode, reducing the second engine speedand load range for DFSO operation, decreasing torque converter slip, anddecreasing the accessory load applied on the engine as the occupancylevel decreases.